Skip to content
https://ipcc.ch

Lighthouse Desktop

· 0 checks — Desktop Lighthouse audit -- Performance, Accessibility, Best Practices, and SEO category breakdown.
SCORE
0
GRADE
FIX
0
REVIEW
0
PASS
0
INFO
0

Detailed Report

Audit breakdown by category with detailed findings.

86

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Performance issues directly impact user engagement and conversion rates.

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

RequestCache TTLTransfer Size
www.ipcc.ch/site/assets/uploads/2026/03/ESCAP-building.png3600.0 s1.4 MiB
/site/assets/uploads/2026/01/giammarco-boscaro-q140lHKzXZ...3600.0 s938.5 KiB
/site/assets/uploads/2025/11/pexels-chris-molloy-220084-1...3600.0 s660.3 KiB
www.ipcc.ch/site/assets/uploads/2017/09/WGII.png3600.0 s581.2 KiB
www.ipcc.ch/site/assets/uploads/2017/09/AR.png3600.0 s483.2 KiB
www.ipcc.ch/site/assets/uploads/2025/06/Reading-Feb26.jpg3600.0 s448.0 KiB
/site/assets/uploads/2026/01/christoffer-engstrom-tjguVu0...3600.0 s424.3 KiB
www.ipcc.ch/site/assets/uploads/2026/04/LAM1-CDR.jpg3600.0 s273.4 KiB
www.ipcc.ch/site/assets/uploads/2017/08/thumbnail_wg1.jpg3600.0 s197.0 KiB
www.ipcc.ch/site/assets/uploads/2017/11/Emissions-1.jpg3600.0 s159.0 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/img/footer_bg1.png3600.0 s155.9 KiB
www.ipcc.ch/site/assets/uploads/2018/03/AR3_4-1-600x600.jpg3600.0 s123.4 KiB
www.ipcc.ch/site/assets/uploads/2024/04/pikist_city-green-copy-600x600.jpg3600.0 s120.9 KiB
www.ipcc.ch/site/assets/uploads/2017/08/wg3.jpg3600.0 s95.0 KiB
www.ipcc.ch/site/assets/uploads/2021/08/ar6_wg1_art2-600x600.jpg3600.0 s94.2 KiB
www.ipcc.ch/site/assets/uploads/2017/09/AR5-WGI-600x600.jpg3600.0 s91.4 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR2_2-600x600.jpg3600.0 s87.6 KiB
connect.facebook.net/en_US/bundle/sdk.js/1200.0 s77.8 KiB
www.ipcc.ch/site/assets/uploads/2026/03/IPCC_64.jpg3600.0 s82.1 KiB
www.ipcc.ch/site/assets/uploads/2019/07/32772680570_aaf0dc2974_b.jpg3600.0 s81.1 KiB
www.ipcc.ch/site/assets/uploads/2022/04/WGIII_AR6_SPM_Cover_darkened-600x600.jpg3600.0 s79.0 KiB
/site/assets/uploads/2022/02/Final-Hi-Res-Version_Cover-i...3600.0 s77.1 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR4_2-600x600.jpg3600.0 s76.4 KiB
www.ipcc.ch/site/assets/uploads/2017/08/wg2.jpg3600.0 s73.9 KiB
www.ipcc.ch/site/assets/uploads/2019/08/SRCCLcover-web-600x600.jpg3600.0 s72.9 KiB
www.ipcc.ch/site/assets/uploads/2018/03/AR3_2-600x600.jpg3600.0 s70.9 KiB
/site/assets/themes/ipcc/resources/bower_components/amcha...3600.0 s64.1 KiB
/site/assets/uploads/2018/02/erin-baker-23393-unsplash111...3600.0 s63.0 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR1_3-600x600.jpg3600.0 s57.0 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR4_5-600x600.jpg3600.0 s56.7 KiB
www.ipcc.ch/site/assets/uploads/2018/03/AR2_3-600x600.jpg3600.0 s54.6 KiB
www.ipcc.ch/site/assets/uploads/2018/03/AR3_1-1-600x600.jpg3600.0 s53.3 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR1_1-600x600.jpg3600.0 s49.9 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR5_3-600x600.jpg3600.0 s45.6 KiB
/site/assets/uploads/1999/03/ian-baldwin-821111112170-uns...3600.0 s43.6 KiB
www.ipcc.ch/site/assets/uploads/2017/09/Big-cloud-formation-600x600.jpg3600.0 s40.6 KiB
/site/assets/uploads/2018/05/chang-qing-16464-unsplash111...3600.0 s40.5 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/img/splash_logos.png3600.0 s38.5 KiB
www.ipcc.ch/site/assets/uploads/2023/03/frontcover-600x600.jpg3600.0 s37.3 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR1_4-600x600.jpg3600.0 s36.3 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR4_1-600x600.jpg3600.0 s36.1 KiB
www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp3600.0 s34.4 KiB
/site/assets/themes/ipcc/resources/fonts/ipccserif-regula...3600.0 s28.5 KiB
www.ipcc.ch/site/assets/uploads/2019/09/srocc-cover-photo-small-600x600.jpg3600.0 s26.1 KiB
www.ipcc.ch/site/assets/uploads/2016/11/AR4SYR_BG-1-600x600.jpg3600.0 s26.0 KiB
www.ipcc.ch/site/assets/uploads/2018/02/AR2WG1BG-600x600.jpg3600.0 s26.0 KiB
/site/assets/themes/ipcc/resources/fonts/ipccsans-medium-...3600.0 s21.9 KiB
/site/assets/themes/ipcc/resources/fonts/ipccsans-regular...3600.0 s21.8 KiB
www.ipcc.ch/site/assets/uploads/2020/06/SLCFsqimg.jpg3600.0 s21.8 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/css/screen.css3600.0 s21.5 KiB
www.ipcc.ch/site/assets/uploads/2017/09/cover-image-for-web-.jpg3600.0 s21.2 KiB
www.ipcc.ch/site/assets/uploads/2018/02/ar1_2-600x600.jpg3600.0 s20.7 KiB
www.google-analytics.com/analytics.js7200.0 s20.9 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/img/footer_logos.png3600.0 s18.3 KiB
/site/assets/themes/ipcc/resources/bower_components/amcha...3600.0 s17.0 KiB
/site/assets/themes/ipcc/resources/bower_components/amcha...3600.0 s15.7 KiB
www.ipcc.ch/site/assets/uploads/2020/06/SLCFimg3.jpg3600.0 s14.7 KiB
www.ipcc.ch/site/assets/uploads/2017/09/splash_clouds1.jpg3600.0 s12.7 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/img/bg_overlay.jpg3600.0 s11.4 KiB
/site/assets/themes/ipcc/resources/bower_components/slick...3600.0 s11.0 KiB
/site/assets/themes/ipcc/resources/bower_components/isoto...3600.0 s10.4 KiB
www.ipcc.ch/site/wp-includes/css/dist/block-library/style.min.css?ver=5.3.153600.0 s6.4 KiB
connect.facebook.net/en_US/sdk.js1200.0 s5.1 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/components/post-grid/post-grid.js3600.0 s5.2 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/img/h7.png3600.0 s5.1 KiB
/site/assets/themes/ipcc/resources/bower_components/amcha...3600.0 s5.1 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/js/global-functions.js3600.0 s4.6 KiB
/site/assets/themes/ipcc/resources/bower_components/isoto...3600.0 s4.5 KiB
www.ipcc.ch/site/assets/plugins/contact-form-7/includes/js/scripts.js?ver=5.0.53600.0 s4.4 KiB
www.ipcc.ch/site/wp-includes/js/jquery/jquery-migrate.min.js?ver=1.4.13600.0 s4.3 KiB
www.ipcc.ch/site/assets/themes/ipcc/resources/fonts/IPCCIcons.ttf?gxqzaz3600.0 s4.3 KiB
/site/assets/themes/ipcc/resources/bower_components/scrol...3600.0 s3.4 KiB
www.ipcc.ch/site/assets/plugins/tablepress/css/default.min.css?ver=1.9.13600.0 s2.9 KiB
/site/assets/themes/ipcc/resources/bower_components/pe-so...3600.0 s2.4 KiB
/site/assets/themes/ipcc/resources/bower_components/norma...3600.0 s2.4 KiB
/site/assets/themes/ipcc/resources/bower_components/pe-so...3600.0 s1.7 KiB
/site/assets/themes/ipcc/resources/bower_components/js-co...3600.0 s1.7 KiB
/site/assets/themes/ipcc/resources/bower_components/stick...3600.0 s1.5 KiB
/site/assets/themes/ipcc/resources/bower_components/amcha...3600.0 s1.4 KiB
/site/assets/themes/ipcc/resources/bower_components/amcha...3600.0 s1.3 KiB
/site/assets/themes/ipcc/resources/bower_components/pe-na...3600.0 s1.1 KiB
/site/assets/themes/ipcc/resources/bower_components/pe-sm...3600.0 s1.0 KiB
www.ipcc.ch/site/wp-includes/js/wp-embed.min.js?ver=5.3.153600.0 s991 B
/site/assets/themes/ipcc/resources/bower_components/gridt...3600.0 s926 B
/site/assets/themes/ipcc/resources/bower_components/paral...3600.0 s918 B
www.ipcc.ch/site/assets/plugins/contact-form-7/includes/css/styles.css?ver=5.0.53600.0 s898 B
/site/assets/themes/ipcc/resources/bower_components/pe-bo...3600.0 s852 B
/site/assets/themes/ipcc/resources/bower_components/pe-eq...3600.0 s649 B
/site/assets/themes/ipcc/resources/bower_components/pe-wi...3600.0 s416 B
www.ipcc.ch/site/assets/themes/ipcc/style.css3600.0 s415 B
www.ipcc.ch/site/assets/themes/ipcc/resources/js/mods.js3600.0 s376 B
www.ipcc.ch/site/assets/themes/ipcc/resources/css/mods.css3600.0 s264 B

Your first network request is the most important. Reduce its latency by avoiding redirects, ensuring a fast server response, and enabling text compression.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Consider setting font-display to swap or optional to ensure text is consistently visible. swap can be further optimized to mitigate layout shifts with font metric overrides.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLEst Savings
/site/assets/themes/ipcc/resources/fonts/ipccserif-regula...105 ms
/site/assets/themes/ipcc/resources/fonts/ipccsans-medium-...90 ms
/site/assets/themes/ipcc/resources/fonts/ipccsans-regular...90 ms
/s/robotocondensed/v31/ieVl2ZhZI2eCN5jzbjEETS9weq8-19K7DQ...55 ms
/s/robotocondensed/v31/ieVl2ZhZI2eCN5jzbjEETS9weq8-19a7DQ...55 ms
www.ipcc.ch/site/assets/themes/ipcc/resources/fonts/IPCCIcons.ttf?gxqzaz50 ms

A forced reflow occurs when JavaScript queries geometric properties (such as offsetWidth) after styles have been invalidated by a change to the DOM state. This can result in poor performance. Learn more about forced reflows and possible mitigations.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:source label:Top function call valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:46.339 source:map[column:30194 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]]]
headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:0.404 source:map[column:31275 line:1 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:17.628 source:map[column:27329 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:1.857 source:map[column:25402 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:0.194 source:map[column:25531 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:0.099 source:map[column:25841 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:0.172 source:map[column:25903 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:1.084 source:map[column:26161 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:0.248 source:map[column:26236 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:13.751 source:map[column:29403 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:2.286 source:map[column:27351 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:5.176 source:map[column:29417 line:2 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:0.787 source:map[column:1251 line:0 type:source-location url:https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/scrollreveal/dist/scrollreveal.min.js urlProvider:network]] map[reflowTime:0.71 source:map[column:31487 line:3 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:0.42 source:map[column:84 line:4 type:source-location url:https://www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp urlProvider:network]] map[reflowTime:0.699 source:map[column:2933 line:10 type:source-location url:https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/isotope/dist/isotope.pkgd.min.js urlProvider:network]] map[reflowTime:0.474 source:map[column:3088 line:10 type:source-location url:https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/isotope/dist/isotope.pkgd.min.js urlProvider:network]] map[reflowTime:0.35 source:map[column:3126 line:10 type:source-location url:https://www.ipcc.ch/site/assets/themes/ipcc/resources/bower_components/isotope/dist/isotope.pkgd.min.js urlProvider:network]]]

Optimize LCP by making the LCP image discoverable from the HTML immediately, and avoiding lazy-loading

Why this matters

Performance issues directly impact user engagement and conversion rates.

lhId: page-0-DIV
nodeLabel: div.page-container > section#home-page-splash-1 > div.section-container > div.section-bg
path: 1,HTML,1,BODY,1,DIV,0,SECTION,0,DIV,0,DIV
selector: div.page-container > section#home-page-splash-1 > div.section-container > div.section-bg
snippet: <div class="section-bg bg-animate" style="background-image: url(&quot;https://www.ipcc.ch/site/assets/uploads/2017/09/spla…&quot;);">

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.
title: Preconnected origins
value: no origins were preconnected
description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.
title: Preconnect candidates

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLTransfer SizeDuration
www.ipcc.ch/site/wp-includes/js/jquery/jquery.js?ver=1.12.4-wp34.4 KiB348 ms
fonts.googleapis.com/css?family=Roboto+Condensed:400,7001.1 KiB268 ms
www.ipcc.ch/site/wp-includes/css/dist/block-library/style.min.css?ver=5.3.156.4 KiB89 ms
www.ipcc.ch/site/wp-includes/js/jquery/jquery-migrate.min.js?ver=1.4.14.3 KiB218 ms
www.ipcc.ch/site/assets/themes/ipcc/resources/css/screen.css21.5 KiB283 ms
www.ipcc.ch/site/assets/plugins/tablepress/css/default.min.css?ver=1.9.12.9 KiB218 ms
www.ipcc.ch/site/assets/themes/ipcc/style.css415 B218 ms
www.ipcc.ch/site/assets/plugins/contact-form-7/includes/css/styles.css?ver=5.0.5898 B218 ms
/site/assets/themes/ipcc/resources/bower_components/norma...2.4 KiB89 ms
www.ipcc.ch/site/assets/themes/ipcc/resources/css/mods.css264 B89 ms
/site/assets/themes/ipcc/resources/bower_components/amcha...5.1 KiB89 ms
/site/assets/themes/ipcc/resources/bower_components/gridt...926 B89 ms

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLResource SizeEst Savings
div.section-posts > div.post > div.preview-content > div.preview-thumbnail div.section-posts > div.post > div.preview-content > div.preview-thumbnail
www.ipcc.ch/site/assets/uploads/2026/03/ESCAP-building.png1.4 MiB1.2 MiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2017/09/WGII.png580.8 KiB518.8 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2017/09/AR.png482.9 KiB442.3 KiB
div.section-posts > div.post > div.preview-content > div.preview-thumbnail div.section-posts > div.post > div.preview-content > div.preview-thumbnail
/site/assets/uploads/2026/01/giammarco-boscaro-q140lHKzXZ...938.1 KiB226.9 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2018/03/AR3_4-1-600x600.jpg123.1 KiB64.5 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2024/04/pikist_city-green-copy-600x600.jpg120.6 KiB62.0 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2021/08/ar6_wg1_art2-600x600.jpg93.9 KiB35.3 KiB
div.section-container > div.section-content > div.section-block > img div.section-container > div.section-content > div.section-block > img
www.ipcc.ch/site/assets/themes/ipcc/resources/img/splash_logos.png38.2 KiB35.1 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2017/09/AR5-WGI-600x600.jpg91.0 KiB32.5 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2018/02/AR2_2-600x600.jpg87.2 KiB28.6 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2022/04/WGIII_AR6_SPM_Cover_darkened-600x600.jpg78.7 KiB20.1 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
/site/assets/uploads/2022/02/Final-Hi-Res-Version_Cover-i...76.8 KiB18.2 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2018/02/AR4_2-600x600.jpg76.1 KiB17.5 KiB
IPCC | WHO | UNEP div.page-container > div#footer-nav > div#footer-logos > img
www.ipcc.ch/site/assets/themes/ipcc/resources/img/footer_logos.png18.0 KiB15.9 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2019/08/SRCCLcover-web-600x600.jpg72.5 KiB13.9 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
www.ipcc.ch/site/assets/uploads/2018/03/AR3_2-600x600.jpg70.6 KiB12.0 KiB
Designed by Habitat Seven div#footer-nav > div#h7 > a > img
www.ipcc.ch/site/assets/themes/ipcc/resources/img/h7.png4.8 KiB4.7 KiB
div.slide > div.block > div.block-content > div.block-thumbnail div.slide > div.block > div.block-content > div.block-thumbnail
/site/assets/uploads/2018/02/erin-baker-23393-unsplash111...62.7 KiB4.1 KiB

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Diagnostics

Minifying CSS files can reduce network payload sizes. Learn how to minify CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 60 ms 5.2 KiB
URLTransfer SizeEst Savings
www.ipcc.ch/site/assets/themes/ipcc/resources/css/screen.css21.5 KiB5.2 KiB

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity. Learn how to reduce unused CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 110 ms 15.6 KiB
URLTransfer SizeEst Savings
www.ipcc.ch/site/assets/themes/ipcc/resources/css/screen.css21.2 KiB15.6 KiB

Many navigations are performed by going back to a previous page, or forwards again. The back/forward cache (bfcache) can speed up these return navigations. Learn more about the bfcache

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failure reasonFailure type
Pages with cache-control:no-store header cannot enter back/forward cache.Actionable
Pages whose main resource has cache-control:no-store cannot enter back/forward cache.Not actionable
Back/forward cache is disabled because some JavaScript network request received resource with Cache-Control: no-store header.Not actionable

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 2.3 KiB
URLTransfer SizeEst Savings
www.ipcc.ch/site/assets/themes/ipcc/resources/components/post-grid/post-grid.js4.9 KiB2.3 KiB

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 239.4 KiB
URLTransfer SizeEst Savings
www.googletagmanager.com/gtag/js?id=G-97J7HJ28MR&cx=c&gtm=4e64k0h2159.0 KiB65.2 KiB
www.googletagmanager.com/gtag/js?id=UA-168918890-1125.0 KiB63.6 KiB
/site/assets/themes/ipcc/resources/bower_components/amcha...63.8 KiB56.9 KiB
connect.facebook.net/en_US/bundle/sdk.js/77.6 KiB53.7 KiB

Large network payloads cost users real money and are highly correlated with long load times. Learn how to reduce payload sizes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLTransfer Size
www.ipcc.ch/site/assets/uploads/2026/03/ESCAP-building.png1.4 MiB
/site/assets/uploads/2026/01/giammarco-boscaro-q140lHKzXZ...938.5 KiB
/site/assets/uploads/2025/11/pexels-chris-molloy-220084-1...660.3 KiB
www.ipcc.ch/site/assets/uploads/2017/09/WGII.png581.2 KiB
www.ipcc.ch/site/assets/uploads/2017/09/AR.png483.2 KiB
www.ipcc.ch/site/assets/uploads/2025/06/Reading-Feb26.jpg448.0 KiB
/site/assets/uploads/2026/01/christoffer-engstrom-tjguVu0...424.3 KiB
www.ipcc.ch/site/assets/uploads/2026/04/LAM1-CDR.jpg273.4 KiB
www.ipcc.ch/site/assets/uploads/2017/08/thumbnail_wg1.jpg197.0 KiB
www.googletagmanager.com/gtag/js?id=G-97J7HJ28MR&cx=c&gtm=4e64k0h2159.0 KiB

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL
div.section-container > div.section-content > div.section-block > img div.section-container > div.section-content > div.section-block > img
www.ipcc.ch/site/assets/themes/ipcc/resources/img/splash_logos.png
IPCC | WHO | UNEP div.page-container > div#footer-nav > div#footer-logos > img
www.ipcc.ch/site/assets/themes/ipcc/resources/img/footer_logos.png
Designed by Habitat Seven div#footer-nav > div#h7 > a > img
www.ipcc.ch/site/assets/themes/ipcc/resources/img/h7.png

More information about the performance of your application. These numbers don't directly affect the Performance score.

Redirects introduce additional delays before the page can be loaded. Learn how to avoid page redirects.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 482 ms
URLTime Spent
ipcc.ch/292 ms
www.ipcc.ch/190 ms
www.ipcc.ch/0.0 ms

Keep the server response time for the main document short because all other requests depend on it. Learn more about the Time to First Byte metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 580 ms
URLTime Spent
www.ipcc.ch/680 ms
●Time to Interactive 2.0 s
●Layout shift culprits
●Optimize DOM size
●LCP breakdown
●Modern HTTP
●Optimize viewport for mobile
●Max Potential First Input Delay 50 ms
●User Timing marks and measures 5 user timings
●JavaScript execution time 0.1 s
●Minimizes main-thread work 0.8 s
●Avoid long main-thread tasks 2 long tasks found
●Avoid non-composited animations 144 animated elements found
●Network Requests
●Network Round Trip Times 20 ms
●Server Backend Latencies 30 ms
●Tasks
●Diagnostics
●Metrics
●Screenshot Thumbnails
●Final Screenshot
●Script Treemap Data
●Resources Summary
●Avoid large layout shifts 3 layout shifts found
○INP breakdown
71

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

Names and labels

When a button doesn't have an accessible name, screen readers announce it as "button", making it unusable for users who rely on screen readers. Learn how to make buttons more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.overlay-content > form#header-search > div#search-btn > button.search-submit div.overlay-content > form#header-search > div#search-btn > button.search-submit

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more about the `alt` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.section-container > div.section-content > div.section-block > img div.section-container > div.section-content > div.section-block > img

Link text (and alternate text for images, when used as links) that is discernible, unique, and focusable improves the navigation experience for screen reader users. Learn how to make links accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
body#page-home > header#main-header > nav#nav-primary > a#nav-primary-logo body#page-home > header#main-header > nav#nav-primary > a#nav-primary-logo
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
div.slide > div.block > div.block-content > a.block-link div.slide > div.block > div.block-content > a.block-link
footer#main-footer > div.page-container > div#footer-banner > a#footer-logo footer#main-footer > div.page-container > div#footer-banner > a#footer-logo
body#page-home > div#search-overlay > a#search-close body#page-home > div#search-overlay > a#search-close
header#sticky-header > div#sticky-content > div.section-container > a#sticky-logo header#sticky-header > div#sticky-content > div.section-container > a#sticky-logo

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Contrast

Low-contrast text is difficult or impossible for many users to read. Learn how to provide sufficient color contrast.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
MENU header#main-header > nav#nav-secondary > a#nav-overlay-trigger > span
ABOUT div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-169 > a
DATA div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-12593 > a
DOCUMENTATION div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-12754 > a
DASHBOARD div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-657 > a
BUREAU PORTAL div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-165 > a
LIBRARY div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-25140 > a
LINKS div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-841 > a
HELP div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-36755 > a
LANGUAGES nav#nav-secondary > div#nav-tertiary > div#nav-secondary-lang > h6
SEARCH div#nav-tertiary > div#nav-secondary-search > a#search-trigger > span
REPORTS div#nav-primary-menu > ul.menu > li > a#menu-link-reports
SYNTHESIS REPORT div#nav-primary-menu > ul.menu > li > a#menu-link-synthesis-report
WORKING GROUPS div#nav-primary-menu > ul.menu > li > a#menu-link-working-groups
ACTIVITIES div#nav-primary-menu > ul.menu > li > a#menu-link-activities
NEWS div#nav-primary-menu > ul.menu > li > a#menu-link-news
CALENDAR div#nav-primary-menu > ul.menu > li > a#menu-link-calendar
FOLLOW div#nav-primary-follow > div.social-widget-wrap > div#follow > span.text
SHARE div#nav-primary-share > div.social-widget-wrap > div#share > span.text
VACANCIES div.section-container > div.section-content > div.section-block > a.btn
Follow the IPCC div.section-content > div#footer-engage-follow > div.section-block-text > h4
The Intergovernmental Panel on Climate Change (IPCC) is active socially – choos… div.section-content > div#footer-engage-follow > div.section-block-text > p
Engage with the IPCC div.section-content > div#footer-engage-participate > div.section-block-text > h4
There are many ways to be involved and participate in the IPCC world. div.section-content > div#footer-engage-participate > div.section-block-text > p
LEARN MORE div#footer-engage-participate > div.section-block-text > p > a.btn

These are opportunities to improve the legibility of your content.

Navigation

Properly ordered headings that do not skip levels convey the semantic structure of the page, making it easier to navigate and understand when using assistive technologies. Learn more about heading order.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body… section#home-page-splash-1 > div.section-container > header.section-header > h3
LATEST footer.section-footer > div.ticker-head > div.ticker-title > h6
FOLLOW div.section-container > aside.section-aside > div.aside-block > h5
MEETING div.post > div.preview-content > div.preview-text > h5
March 24, 2026 div.post > div.preview-content > div.preview-text > h6
March 3, 2026 div.post > div.preview-content > div.preview-text > h6
February 10, 2026 div.post > div.preview-content > div.preview-text > h6
January 27, 2026 div.post > div.preview-content > div.preview-text > h6
January 12, 2026 div.post > div.preview-content > div.preview-text > h6
December 1, 2025 div.post > div.preview-content > div.preview-text > h6
Synthesis Report div.slide > div.block > div.block-caption > h5
Special Report div.slide > div.block > div.block-caption > h5
Working Group I div.post > div.preview-content > div.preview-text > h4
SEVENTH ASSESSMENT REPORT div.nav-reports-container > div.report-menu-column > div.report-menu-list > h5

These are opportunities to improve keyboard navigation in your application.

Internationalization and localization

If a page doesn't specify a `lang` attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more about the `lang` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html html

These are opportunities to improve the interpretation of your content by users in different locales.

Best practices

Touch targets with sufficient size and spacing help users who may have difficulty targeting small controls to activate the targets. Learn more about touch targets.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
DASHBOARD div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-657 > a
HELP div.menu-secondary-navigation-container > ul#menu-secondary-navigation > li#menu-item-36755 > a

One main landmark helps screen reader users navigate a web page. Learn more about landmarks.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html html

These items highlight common accessibility best practices.

○Interactive controls are keyboard focusable
○Interactive elements indicate their purpose and state
○The page has a logical tab order
○Visual order on the page follows DOM order
○User focus is not accidentally trapped in a region
○The user's focus is directed to new content added to the page
○HTML5 landmark elements are used to improve navigation
○Offscreen content is hidden from assistive technology
○Custom controls have associated labels
○Custom controls have ARIA roles
●`[aria-*]` attributes match their roles
●`[aria-hidden="true"]` is not present on the document `<body>`
●`[role]`s have all required `[aria-*]` attributes
●`[role]` values are valid
●`[aria-*]` attributes have valid values
●`[aria-*]` attributes are valid and not misspelled
●Form elements have associated labels
●`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.
●ARIA attributes are used as specified for the element's role
●`[aria-hidden="true"]` elements do not contain focusable descendents
●Elements use only permitted ARIA attributes
●Document has a `<title>` element
●Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
●List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements
●No element has a `[tabindex]` value greater than 0
●Deprecated ARIA roles were not used
●Identical links have the same purpose.
○`[accesskey]` values are unique
○`button`, `link`, and `menuitem` elements have accessible names
○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.
○ARIA input fields have accessible names
○ARIA `meter` elements have accessible names
○ARIA `progressbar` elements have accessible names
○Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.
○`[role]`s are contained by their required parent element
○Elements with the `role=text` attribute do not have focusable descendents.
○ARIA toggle fields have accessible names
○ARIA `tooltip` elements have accessible names
○ARIA `treeitem` elements have accessible names
○The page contains a heading, skip link, or landmark region
○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.
○Definition list items are wrapped in `<dl>` elements
○ARIA IDs are unique
○No form fields have multiple labels
○`<frame>` or `<iframe>` elements have a title
○`<html>` element has a valid value for its `[lang]` attribute
○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.
○Input buttons have discernible text.
○`<input type="image">` elements have `[alt]` text
○Links are distinguishable without relying on color.
○The document does not use `<meta http-equiv="refresh">`
○`<object>` elements have alternate text
○Select elements have associated label elements.
○Skip links are focusable.
○Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.
○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.
○`[lang]` attributes have a valid value
○`<video>` elements contain a `<track>` element with `[kind="captions"]`
○Tables have different content in the summary attribute and `<caption>`.
○All heading elements contain content.
○Uses ARIA roles only on compatible elements
○Image elements do not have `[alt]` attributes that are redundant text.
○Elements with visible text labels have matching accessible names.
○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.
○`<td>` elements in a large `<table>` have one or more table headers.
81

Best Practices

Trust and Safety

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being served over HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more about HTTPS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Insecure URLRequest Resolution
www.ipcc.ch/Allowed
●Avoids deprecated APIs
●Avoids third-party cookies
●Allows users to paste into input fields
●Avoids requesting the geolocation permission on page load
●Avoids requesting the notification permission on page load
●Displays images with correct aspect ratio
●Serves images with appropriate resolution
●Page has the HTML doctype
●Properly defines charset
●No browser errors logged to the console
●No issues in the `Issues` panel in Chrome Devtools
●Ensure CSP is effective against XSS attacks
●Use a strong HSTS policy
●Ensure proper origin isolation with COOP
●Mitigate DOM-based XSS with Trusted Types
●Detected JavaScript libraries
●Page has valid source maps
○Redirects HTTP traffic to HTTPS
○Mitigate clickjacking with XFO or CSP
77

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

Content Best Practices

Meta descriptions may be included in search results to concisely summarize page content. Learn more about the meta description.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Descriptive link text helps search engines understand your content. Learn how to make links more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Link destinationLink Text
www.ipcc.ch/2026/04/14/pr-ipcc-cdrt-mr-first-lead-author-meeting/Read more
www.ipcc.ch/2026/03/19/ipccs-sixty-fourth-plenary-in-bangkok-thailand/Read more
www.ipcc.ch/2025/11/19/calltficdrccus/Read more
www.ipcc.ch/2026/03/27/ipcc-64th-plenary-session/Read more
www.ipcc.ch/2026/04/14/pr-ipcc-cdrt-mr-first-lead-author-meeting/Read more
www.ipcc.ch/2026/03/19/ipccs-sixty-fourth-plenary-in-bangkok-thailand/Read more
www.ipcc.ch/2025/11/19/calltficdrccus/Read more
www.ipcc.ch/2026/03/27/ipcc-64th-plenary-session/Read more
www.ipcc.ch/2026/04/14/pr-ipcc-cdrt-mr-first-lead-author-meeting/Read more
www.ipcc.ch/about/engage_with_the_ipccLEARN MORE
www.ipcc.ch/about/engage_with_the_ipcc/LEARN MORE

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more about the `alt` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.section-container > div.section-content > div.section-block > img div.section-container > div.section-content > div.section-block > img

Format your HTML in a way that enables crawlers to better understand your app’s content.

○Structured data is valid
●Page isn’t blocked from indexing
●Document has a `<title>` element
●Page has successful HTTP status code
●Links are crawlable
●robots.txt is valid
●Document has a valid `hreflang`
●Document has a valid `rel=canonical`

Send Feedback