The Post-1998 Hiatus

Plods On…Regionally

Image Source: Gan et al., 2019

North America (180-0°N, 15-60°N) has been characterized as a “major cooling center” by the authors of a new paper (Gan et al., 2019) published in Earth and Space Science.

The continent warmed from 1982-1998, but a cooling trend since 1998 has nearly wiped out all the previous warming.

Overall, there has been no significant temperature change in North America since 1982.

The warming and cooling trends, especially the daily temperature minimum (Tmin), are well-correlated (r=0.71) with the path of the Atlantic Multidecadal Oscillation (AMO) during 1950-2014, leading the authors to conclude that the temperature trends over this 32-year period are “a result of” natural changes in the AMO.

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Gan et al., 2019

The Key Role of Atlantic Multidecadal Oscillation
in Minimum Temperature Over North America
During Global Warming Slowdown

“Daily Minimum temperature (Tmin) is an important variable in both global and regional climate changes, and its variability can greatly affect the ecological system. In the early 21st century, warming slowdown is seen over the North Hemisphere and North America is one of the major cooling centers.”

“In this study, we found that Tmin experienced an obvious decline in North America during warming slowdown period. Such Tmin decline is closely related to the Atlantic Multidecadal Oscillation (AMO), the correlation between the decadal components of Tmin and AMO reached 0.71 during 1950-2014.”

“According to composite analysis, the AMO on the positive (negative) phase takes two low-pressure (high-pressure) systems in the northeastern Pacific and the North Atlantic at night, accompanied by cyclonic (anticyclonic) circulations and warm (cold) advection in North America. Therefore, the analyses conclude that the Tmin decline during warming slowdown period is a result of the synchronous decrease of the AMO. The results emphasize the key role of AMO on the decadal variation of Tmin in North America.”

Image Source: Gan et al., 2019

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Another new paper renews the global warming “hiatus” debate and documents a 21st century cooling trend in northern China that also effectively snuffs out the previous decades of warming for the region.

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Li et al., 2019

Satellite-based regional warming

hiatus in China and its implication

“Global warming ‘stalled’ or ‘paused’ for the period 1998–2012, as claimed by the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) (IPCC, 2013). However, the early drafts of IPCC AR5 have no detailed explanation for this “hiatus” since 111 of 114 climate models in the CMIP5 earth system model did not verify this phenomenon. … In 2017, after a wave of scientific publications and public debate, the climate models as reported in IPCC remain debates, including definitions of “hiatus” and datasets (Medhaug et al., 2017).”

Image Source: Li et al., 2019

“The slowdown in global warming since 1998, often termed the global warming hiatus. Reconciling the “hiatus” is a main focus in the 2013 climate change conference. Accurately characterizing the spatiotemporal trends in surface air temperature (SAT) is helps to better understand the “hiatus” during the period. This article presents a satellite-based regional warming simulation to diagnose the “hiatus” for 2001–2015 in China. Results show that the rapid warming is mainly in western and southern China, such as Yunnan (mean ± standard deviation: 0.39 ± 0.26 °C (10 yr)−1 ), Tibet (0.22 ± 0.25 °C (10 yr)−1), Taiwan (0.21 ± 0.25 °C (10 yr)−1), and Sichuan (0.19± 0.25 °C (10 yr)−1). On the contrary, there is a cooling trend by 0.29 ± 0.26 °C (10 yr)−1 in northern China during the recent 15 yr, where a warming rate about 0.38 ± 0.11 °C (10 yr)−1 happened for 1960–2000. Overall, satellite simulation shows that the warming rate is reduced to −0.02 °C (10 yr)−1. The changes in underlying surface, Earth’s orbit, solar radiation and atmospheric counter radiation (USEOSRACR) cause China’s temperature rise about 0.02 °C (10 yr)−1. A combination of greenhouse gases (GHGs) and other natural forcing (ONAT, predominately volcanic activity, and atmosphere and ocean circulation) explain another part of temperature trend by approximately −0.04 °C (10 yr)−1. We conclude that there is a regional warming hiatus, a pause or a slowdown in China, and imply that GHGs-induced warming is suppressed by ONAT [other natural forcing] in the early 21st century.”

Image Source: Li et al., 2019

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March 14, 2019 at 08:30AM

Students striking over climate change inaction have been described as victims of “politically correct teaching” and include some who are “barely literate or numerate”.

Thousands of young people across the country — and countless more worldwide — will walk out of school on Friday in a global day of action to incite governments to do more to reduce fossil fuel emissions.

Organisers believe crowd numbers will be triple those of student strikes held in November.

But Dr Kevin Donnelly, a conservative commentator and senior research fellow at the Australian Catholic University, claimed the movement was the product of “biased” academics and failings in education.

“I’ve just been on the Strike 4 Climate webpage, where you’ve got seven or eight-year-old kids barely out of nappies being involved in a strike,” he told ABC Radio Adelaide.

“A lot of these students are barely literate or numerate.

“I think it’s absurd.”

Dr Donnelly, an education expert who has written about political correctness which he says is “destroying” Australia, said 1,000 international scientists had dissenting views about the cause and extent of climate change.

He said there had been next to no recognition of this by academics who support the striking students.

“It’s all very well to be politically correct, but there’s no rationality or reason behind it that stands up,” he said, adding that students should protest on the weekend so they didn’t miss school.

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March 14, 2019 at 07:39AM

Guest ridiculing by David Middleton I couldn’t make this sort of schist up if I was trying… CLIMATE It’s 2050 And This Is How We Stopped Climate Change March 11, 20195:03 AM ET Heard on Morning Edition Dan Charles When NPR interviewed Rep. Alexandria Ocasio-Cortez in February about her Green New Deal, she said that…

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March 14, 2019 at 07:06AM

Dinosaurs were unaffected by long-term climate changes and flourished before their sudden demise by asteroid strike.

Scientists largely agree that an asteroid impact, possibly coupled with intense volcanic activity, wiped out the dinosaurs at the end of the Cretaceous period 66 million years ago.

However, there is debate about whether dinosaurs were flourishing before this, or whether they had been in decline due to long-term changes in climate over millions of years.

Previously, researchers used the fossil record and some mathematical predictions to suggest dinosaurs may have already been in decline, with the number and diversity of species falling before the asteroid impact.

Now, in a new analysis that models the changing environment and dinosaur species distribution in North America, researchers from Imperial College London, University College London and University of Bristol have shown that dinosaurs were likely not in decline before the meteorite.

Lead researcher Alessandro Chiarenza, a PhD student in the Department of Earth Science and Engineering at Imperial, said: “Dinosaurs were likely not doomed to extinction until the end of the Cretaceous, when the asteroid hit, declaring the end of their reign and leaving the planet to animals like mammals, lizards and a minor group of surviving dinosaurs: birds.”

“The results of our study suggest that dinosaurs as a whole were adaptable animals, capable of coping with the environmental changes and climatic fluctuations that happened during the last few million years of the Late Cretaceous. Climate change over prolonged time scales did not cause a long-term decline of dinosaurs through the last stages of this period.”

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March 14, 2019 at 06:55AM