{"id":268044,"date":"2023-07-18T12:51:42","date_gmt":"2023-07-18T10:51:42","guid":{"rendered":"https:\/\/climatescience.press\/?p=268044"},"modified":"2023-07-18T12:51:44","modified_gmt":"2023-07-18T10:51:44","slug":"is-the-dry-getting-drier","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=268044","title":{"rendered":"Is The Dry Getting Drier?"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

<\/p>\n\n\n\n

From Watts Up With That?<\/a><\/p>\n\n\n\n

Guest Post by Willis Eschenbach<\/em><\/strong><\/p>\n\n\n\n

So I was wandering through the marvelous\u00a0KNMI website<\/a>, and I came across data for the\u00a0Palmer\u00a0Self-Correcting\u00a0Drought Severity Index<\/a>. This is an index that measures the drought conditions in some given area. The\u00a0source website<\/a>\u00a0says:<\/p>\n\n\n\n

\n

The scPDSI (self-correcting Palmer Drought Severity Index) is a variant on the original PDSI of Palmer (1965), with the aim to make results from different climate regimes more comparable. As with the PDSI, the scPDSI is calculated from time series of precipitation and temperature, together with fixed parameters related to the soil\/surface characteristics at each location.<\/em><\/p>\n<\/blockquote>\n\n\n\n

Now, the KNMI site only offers linear trends of data. But if you look at the bottom of the KNMI page linked above, or other pages at that level of inquiry, you\u2019ll find that there is an option to download the NetCDF version of the data. As in this case, this NetCDF data is often gridded.<\/p>\n\n\n\n

And using that NetCDF gridded file lets me make a graphic showing the average scPDSI for the globe.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 1. Yes, indeed, Australia is a dry country<\/em><\/p>\n\n\n\n

Note that the long-term averages range from minus 2.5 (very dry) to 1.9 (pretty wet). Here, to the same scale, is the monthly global average scPDSI.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 2. Monthly global average self-correcting Palmer Drought Severity Index (scPDSI).<\/em><\/p>\n\n\n\n

No overall change in the scPDSI over the last 120 years\u2014droughts are not becoming either more or less frequent or intense \u2026 go figure.<\/p>\n\n\n\n

Having gotten that far, I thought I\u2019d see what the IPCC Sixth Assessment Report (AR6) has to say about droughts. Here are couple of quotes:<\/p>\n\n\n\n

\n

It is an established fact that human-induced greenhouse gas emissions have led to an increased frequency and\/or intensity of some weather and climate extremes since pre-industrial time, in particular for temperature extremes. Evidence of observed changes in extremes and their attribution to human influence (including greenhouse gas and aerosol emissions and landuse changes) has strengthened since AR5, in particular for extreme precipitation, droughts, tropical cyclones and compound extremes (including dry\/hot events and fire weather).<\/p>\n\n\n\n

SOURCE<\/a><\/p>\n<\/blockquote>\n\n\n\n

My rule of thumb is that most of the time when the IPCC says something is an \u201cestablished fact\u201d \u2026 it isn\u2019t. Here\u2019s another of their claims:<\/p>\n\n\n\n

\n

In summary, there is\u00a0high confidence<\/em>\u00a0that concurrent heatwaves and droughts have increased in frequency over the last century at the global scale due to human influence.<\/p>\n\n\n\n

SOURCE<\/a><\/p>\n<\/blockquote>\n\n\n\n

Both of those made me say \u201cHmmm\u201d, so I thought I\u2019d take a look to see what they are calling \u201cheatwaves\u201d, \u201cdroughts\u201d, and\u00a0\u201chigh confidence\u201d<\/em>. From the glossary of the Working Group where those quotes are found, we have:<\/p>\n\n\n\n

\n

Heatwave<\/strong>: A period of abnormally hot weather, often defined with reference to a relative temperature threshold, lasting from two days to months. Heatwaves and warm spells have various and, in some cases, overlapping definitions.<\/em><\/p>\n\n\n\n

Drought<\/strong>: An exceptional period of water shortage for existing ecosystems and the human population (due to low rainfall, high temperature, and\/or wind).<\/em><\/p>\n\n\n\n

SOURCE<\/a><\/p>\n<\/blockquote>\n\n\n\n

I suppose it might be possible for definitions of measurable phenomena to be more vague, but you\u2019d have to work at it. How on earth can you have\u00a0\u201chigh confidence\u201d<\/em>\u00a0in claims involving totally undefined terms? And a two-day \u201cheatwave\u201d? Say what? That\u2019s not a wave, that\u2019s a tiny ripple.<\/p>\n\n\n\n

Next, here\u2019s how they assign \u201chigh confidence\u201d. Not with mathematics or statistics, as you might imagine, but by squinting at it from across the room and making a value judgment based on \u201cevidence\u201d and \u201cagreement\u201d.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 3. IPCC matrix for making value judgments regarding \u201cconfidence\u201d.<\/em><\/p>\n\n\n\n

So how can they have\u00a0\u201chigh confidence\u201d\u00a0<\/em>that\u00a0\u201d concurrent heatwaves and droughts have increased in frequency\u201d\u00a0<\/em>over the last century when they haven\u2019t even bothered to establish clear, bright-line definitions for either heatwaves or droughts? This is fast approaching simply throwing darts at the above confidence matrix \u2026<\/p>\n\n\n\n

Having seen that the IPCC is merely issuing its usual meaningless pabulum, I continued my investigation of the scPDSI. I moved on to looking at the 120-year trends by geographical areas. Here\u2019s that graph:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 4. Century-long trends in the self-correcting Palmer Drought Severity Index.<\/em><\/p>\n\n\n\n

Some points of note. First, there\u2019s no overall trend. Next, almost nowhere has there been a change of more than \u00b1 0.1 units per century. Next, the southwestern US has gotten wetter and the rest has gotten drier. And Australia, as usual \u2026 drier. But again, not much.<\/p>\n\n\n\n

Seeing that graphic made me wonder about the oft-repeated claim that wet areas are getting wetter and dry areas are getting drier. For example, a study in Nature magazine says:<\/p>\n\n\n\n

\n

The \u201cdry gets drier, wet gets wetter\u201d (DGDWGW) paradigm is widely accepted in global moisture change.<\/em><\/p>\n<\/blockquote>\n\n\n\n

To determine if this is true, we can use a scatterplot of the trend in scPDSI levels (Fig. 4) versus the average scPDSI levels. This gives us the following:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 5. Scatterplot, trend vs average, self-correcting Palmer Drought Severity Index<\/em>.<\/p>\n\n\n\n

Interesting. Most of the world has an average scPDSI between -1 and +1 (bottom scale). There\u2019s little trend in there. But in the dry areas, less than -1, the dryer it is, the wetter it\u2019s getting. And the same is true above +1, the wetter it is, the dryer it\u2019s getting.<\/p>\n\n\n\n

Finally, I made a video of the annual changes in scPDSI around the globe. Here\u2019s that graphic:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Figure 6. Video, changes in annual average scPDSI.<\/em><\/p>\n\n\n\n

My conclusion from that? Ignore the hype about droughts. There\u2019s almost always a hair-raising drought going on somewhere on this lovely planet.<\/p>\n\n\n\n

In closing, to show there\u2019s nothing new under the sun, here\u2019s a long-term look at drought conditions in the American west \u2026<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Good thing that the now-ubiquitous Climate Snowflakes weren\u2019t around during the 200-year drought, the folks back then would never have heard the end of their whining \u2026<\/p>\n\n\n\n

My very best to everyone,<\/p>\n\n\n\n

w.<\/p>\n\n\n\n

Heard It Before Note:<\/strong> When you comment please quote the exact words you\u2019re discussing. It avoids endless problems and misunderstanding.<\/p>\n\n\n\n

\n\n\n\n

Editor\u2019s note. For general reference on droughts<\/a> and other topics, visit EveryThingClimate.com<\/a><\/p>\n\n\n\n

<\/p>\n","protected":false},"excerpt":{"rendered":"

Now, the KNMI site only offers linear trends of data. But if you look at the bottom of the KNMI page linked above, or other pages at that level of inquiry, you\u2019ll find that there is an option to download the NetCDF version of the data. As in this case, this NetCDF data is often gridded.<\/p>\n","protected":false},"author":121246920,"featured_media":268061,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1],"tags":[691821171,691821169,691821170],"class_list":["post-268044","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-dry","tag-knmi-page","tag-palmer-self-correcting-drought-severity-index","fallback-thumbnail"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2023\/07\/00ThinkstockPhotos-469723319-1600x1200-1.jpg?fit=1600%2C1200&ssl=1","jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/paxLW1-17Ji","jetpack-related-posts":[{"id":426268,"url":"https:\/\/climatescience.press\/?p=426268","url_meta":{"origin":268044,"position":0},"title":"The Data: Dutch Meteorological Institute Reinstates Early 20th Century Heat Waves It Had Erased Earlier","author":"uwe.roland.gross","date":"02\/15\/2026","format":false,"excerpt":"Victory for climate skeptics, science in the Netherlands\u2026erased historical heat waves get reinstated","rel":"","context":"In \"climate skeptics\"","block_context":{"text":"climate skeptics","link":"https:\/\/climatescience.press\/?tag=climate-skeptics"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2026\/02\/AQO3J7syICTURDr04nuzDp7xaPj6NQqyE9PEq-7WrtKxR7CYW8fOsbYErHlGeXE-9ItKJehYFREheVU1Ug3QN07UhixMlDopKqRS2HoYlK-bAU3mLl_eCuLezUWUk4MR.jpeg?fit=1200%2C662&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2026\/02\/AQO3J7syICTURDr04nuzDp7xaPj6NQqyE9PEq-7WrtKxR7CYW8fOsbYErHlGeXE-9ItKJehYFREheVU1Ug3QN07UhixMlDopKqRS2HoYlK-bAU3mLl_eCuLezUWUk4MR.jpeg?fit=1200%2C662&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2026\/02\/AQO3J7syICTURDr04nuzDp7xaPj6NQqyE9PEq-7WrtKxR7CYW8fOsbYErHlGeXE-9ItKJehYFREheVU1Ug3QN07UhixMlDopKqRS2HoYlK-bAU3mLl_eCuLezUWUk4MR.jpeg?fit=1200%2C662&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2026\/02\/AQO3J7syICTURDr04nuzDp7xaPj6NQqyE9PEq-7WrtKxR7CYW8fOsbYErHlGeXE-9ItKJehYFREheVU1Ug3QN07UhixMlDopKqRS2HoYlK-bAU3mLl_eCuLezUWUk4MR.jpeg?fit=1200%2C662&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2026\/02\/AQO3J7syICTURDr04nuzDp7xaPj6NQqyE9PEq-7WrtKxR7CYW8fOsbYErHlGeXE-9ItKJehYFREheVU1Ug3QN07UhixMlDopKqRS2HoYlK-bAU3mLl_eCuLezUWUk4MR.jpeg?fit=1200%2C662&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":424744,"url":"https:\/\/climatescience.press\/?p=424744","url_meta":{"origin":268044,"position":1},"title":"Dutch climate skeptics vindicated: KNMI reinstates seven pre-1950 heatwaves after long battle","author":"uwe.roland.gross","date":"02\/05\/2026","format":false,"excerpt":"Seven years after Dutch skeptics first challenged KNMI\u2019s temperature adjustments, the institute has reinstated seven \u201clost\u201d pre-1950 heatwaves at De Bilt \u2014 validating claims of over-correction that had erased 16 out of 23 historical extremes. 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Instead of actually responding to the specific points raised, they merely regurgitated their Press Release:","rel":"","context":"In \"extreme rainfall\"","block_context":{"text":"extreme rainfall","link":"https:\/\/climatescience.press\/?tag=extreme-rainfall"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/07\/OIG-71-1.jpg?fit=1024%2C1024&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/07\/OIG-71-1.jpg?fit=1024%2C1024&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/07\/OIG-71-1.jpg?fit=1024%2C1024&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/climatescience.press\/wp-content\/uploads\/2025\/07\/OIG-71-1.jpg?fit=1024%2C1024&ssl=1&resize=700%2C400 2x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/268044","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/users\/121246920"}],"replies":[{"embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=268044"}],"version-history":[{"count":12,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/268044\/revisions"}],"predecessor-version":[{"id":268063,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/posts\/268044\/revisions\/268063"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=\/wp\/v2\/media\/268061"}],"wp:attachment":[{"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=268044"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=268044"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/climatescience.press\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=268044"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}