{"id":343639,"date":"2024-09-18T17:06:43","date_gmt":"2024-09-18T15:06:43","guid":{"rendered":"https:\/\/climatescience.press\/?p=343639"},"modified":"2024-09-18T17:06:45","modified_gmt":"2024-09-18T15:06:45","slug":"new-study-21st-century-megadrought-in-the-sw-usa-caused-by-45-years-of-east-central-pacific-cooling","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=343639","title":{"rendered":"New Study: 21st Century Megadrought In The SW USA Caused By 45 Years Of East\/Central Pacific Cooling"},"content":{"rendered":"\n
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From NoTricksZone<\/a><\/p>\n\n\n\n

By\u00a0Kenneth Richard<\/a><\/em><\/p>\n\n\n\n

Climate models failed to simulate the observed 1970-2014 Pacific Ocean cooling. The 21st<\/sup>\u00a0century southwestern US megadrought has been linked to this cooling, which \u201cmay have been caused by a forced response to greenhouse gas emissions.\u201d<\/strong><\/p>\n\n\n\n

A new study<\/a><\/strong> provides a fresh look at the circular, self-contradictory reasoning that proponents of the anthropogenic global warming (AGW) narrative routinely employ.<\/p>\n\n\n\n

The authors acknowledge that the Central and East Pacific region has been cooling since 1970, and that climate models failed to simulate this cooling. The modeling failure stems from the assumption that rising greenhouse gas emissions lead to warming, not over four decades of cooling.<\/p>\n\n\n\n

\u201cWhile AO-GCMs [climate models] predicted a warming SST trend in the Central and East Pacific, the region instead experienced a cooling SST trend from 1970 to 2014\u2026\u201d<\/em><\/p>\n\n\n\n

After insisting that \u201cinternal atmospheric variability has a larger role than SST forcing in explaining SWUS [Southwestern United States] precipitation variance,\u201d and that \u201cmost historical droughts are unrelated to SST [sea surface temperature] forcing,\u201d the authors nonetheless pivot, explaining that only during recent decades is the SWUS megadrought causally linked to SST forcing.<\/p>\n\n\n\n

\u201cIn this study, we confirmed the connection between the Equatorial Pacific SST trend pattern and SWUS precipitation trends with Green\u2019s function approach, which allows us to establish a causal link between SST and precipitation.\u201d<\/em><\/p>\n\n\n\n

But the SST forcing that suddenly explains recent SWUS drought trends (after not explaining these trends historically) is not the sign expected with rising greenhouse gas (GHG) emissions. No, drought has not been caused by warmer SSTs, but cooler<\/em> SSTs. They say warmer SSTs will lead to a wetter climate, or less drought.<\/p>\n\n\n\n

\u201c\u2026a cooling SST trend from 1970 to 2014\u2026which potentially led to the observed megadrought in the SWUS due to a decrease in precipitation.\u201d<\/em><\/p>\n\n\n\n

\u201cIf the Central and East Pacific continue cooling, a prolonged period of drought is more likely to continue in the SWUS.\u201d<\/em><\/p>\n\n\n\n

However, in the future, warmer East and Central Pacific SSTs due to rising GHGs are expected (according to modeling) to cause less precipitation, or more SWUS drought. So over 40 years of cooling explains drought now, but sometime in the future warming will explain drought\u2026even though neither warming or cooling SSTs explained SWUS drought historically.<\/p>\n\n\n\n

\u201cAt least part of the megadrought was related to a lack of precipitation from the cooling Central and East Pacific, rather than due to a significant increase in evapotranspiration from global warming, which will likely cause droughts in the future as anthropogenic climate change worsens.\u201d<\/em><\/p>\n\n\n\n

But it\u2019s worse than we thought. The authors assert the cooling SSTs causally linked to the 1970s-to-present SWUS megadrought \u2013 but that may not be the cause of drought in the future \u2013 may be explained by \u2013 yes, indeed \u2013 rising GHG concentrations. GHG forcing leads to warming SSTs \u2013 which, again, may not cause drought now, but may in the future. And yet the recent decades of cooling SSTs may be a response to the rising GHGs too. Rising GHG concentrations may simultaneously cause warming SSTs and cooling SSTs.<\/p>\n\n\n\n

\u201cThe cooling of the Central and East Pacific not simulated by AO-GCMs [climate models] may have been caused by a forced response to greenhouse gas emissions.\u201d<\/em><\/p>\n\n\n\n

So let\u2019s review what the authors found with a \u201cPlain Language Summary\u201d of own.<\/p>\n\n\n\n

Until recent decades, internal atmospheric variability explained historical trends in drought. Warming or cooling SST trends did not. Then, in recent decades, a cooling SST trend (1970-2014) has been \u201cconfirmed\u201d as the causal link to the SWUS megadrought. In the future, however, warming SSTs may cause SWUS megadrought. And both the warming and cooling trends in the SWUS are (and have been) caused by the same mechanism: rising GHGs.<\/p>\n\n\n\n

It would appear the modern version of what constitutes peer-reviewed \u201cclimate science\u201d has devolved into something resembling more of a creative writing exercise than actual science.<\/p>\n\n\n\n

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Image Source:\u00a0Alessi and Rugenstein, 2024<\/a><\/strong><\/figcaption><\/figure>\n\n\n\n

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