Climate change widespread, rapid, and intensifying: IPCC

Date:
August 9, 2021
Source:
Intergovernmental Panel on Climate Change (IPCC)
Summary:
Scientists are observing changes in the Earth's climate in every
region and across the whole climate system, according to the latest
IPCC Report.

Many of the changes observed in the climate are unprecedented in
thousands, if not hundreds of thousands of years, and some of the
changes already set in motion -- such as continued sea level rise --
are irreversible over hundreds to thousands of years.



FULL STORY ========================================================================== [Climate change photo | Credit: (c) jozsitoeroe / stock.adobe.com]
Climate change photo concept, thermometer on earth (stock image).

Credit: (c) jozsitoeroe / stock.adobe.com [Climate change photo |
Credit: (c) jozsitoeroe / stock.adobe.com] Climate change photo concept, thermometer on earth (stock image).

Credit: (c) jozsitoeroe / stock.adobe.com Close Scientists are observing changes in the Earth's climate in every region and across the whole
climate system, according to the latest Intergovernmental Panel on Climate Change (IPCC) Report, released today. Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of
years, and some of the changes already set in motion -- such as continued
sea level rise -- are irreversible over hundreds to thousands of years.


========================================================================== However, strong and sustained reductions in emissions of carbon dioxide
(CO2) and other greenhouse gases would limit climate change. While
benefits for air quality would come quickly, it could take 20-30 years to
see global temperatures stabilize, according to the IPCC Working Group
I report, Climate Change 2021: the Physical Science Basis, approved on
Friday by 195 member governments of the IPCC, through a virtual approval session that was held over two weeks starting on July 26.

The Working Group I report is the first installment of the IPCC's Sixth Assessment Report (AR6), which will be completed in 2022.

"This report reflects extraordinary efforts under exceptional
circumstances," said Hoesung Lee, Chair of the IPCC. "The innovations in
this report, and advances in climate science that it reflects, provide
an invaluable input into climate negotiations and decision-making."
Faster warming The report provides new estimates of the chances of
crossing the global warming level of 1.5DEGC in the next decades, and
finds that unless there are immediate, rapid and large-scale reductions
in greenhouse gas emissions, limiting warming to close to 1.5DEGC or
even 2DEGC will be beyond reach.



==========================================================================
The report shows that emissions of greenhouse gases from human activities
are responsible for approximately 1.1DEGC of warming since 1850-1900,
and finds that averaged over the next 20 years, global temperature
is expected to reach or exceed 1.5DEGC of warming. This assessment is
based on improved observational datasets to assess historical warming,
as well progress in scientific understanding of the response of the
climate system to human-caused greenhouse gas emissions.

"This report is a reality check," said IPCC Working Group I Co-Chair
Vale'rie Masson-Delmotte. "We now have a much clearer picture of the past, present and future climate, which is essential for understanding where
we are headed, what can be done, and how we can prepare." Every region
facing increasing changes Many characteristics of climate change directly depend on the level of global warming, but what people experience is
often very different to the global average. For example, warming over
land is larger than the global average, and it is more than twice as
high in the Arctic.

"Climate change is already affecting every region on Earth, in multiple
ways.

The changes we experience will increase with additional warming," said
IPCC Working Group I Co-Chair Panmao Zhai.



==========================================================================
The report projects that in the coming decades climate changes will
increase in all regions. For 1.5DEGC of global warming, there will be increasing heat waves, longer warm seasons and shorter cold seasons. At
2DEGC of global warming, heat extremes would more often reach critical tolerance thresholds for agriculture and health, the report shows.

But it is not just about temperature. Climate change is bringing multiple different changes in different regions -- which will all increase with
further warming. These include changes to wetness and dryness, to winds,
snow and ice, coastal areas and oceans. For example:
* Climate change is intensifying the water cycle. This brings
more intense
rainfall and associated flooding, as well as more intense drought
in many regions.

* Climate change is affecting rainfall patterns. In high latitudes,
precipitation is likely to increase, while it is projected to
decrease over large parts of the subtropics. Changes to monsoon
precipitation are expected, which will vary by region.

* Coastal areas will see continued sea level rise throughout the 21st
century, contributing to more frequent and severe coastal flooding
in low-lying areas and coastal erosion. Extreme sea level events
that previously occurred once in 100 years could happen every year
by the end of this century.

* Further warming will amplify permafrost thawing, and the loss
of seasonal
snow cover, melting of glaciers and ice sheets, and loss of summer
Arctic sea ice.

* Changes to the ocean, including warming, more frequent marine
heatwaves,
ocean acidification, and reduced oxygen levels have been clearly
linked to human influence. These changes affect both ocean
ecosystems and the people that rely on them, and they will continue
throughout at least the rest of this century.

* For cities, some aspects of climate change may be amplified,
including
heat (since urban areas are usually warmer than their surroundings),
flooding from heavy precipitation events and sea level rise in
coastal cities.

For the first time, the Sixth Assessment Report provides a more
detailed regional assessment of climate change, including a focus on
useful information that can inform risk assessment, adaptation, and
other decision-making, and a new framework that helps translate physical changes in the climate -- heat, cold, rain, drought, snow, wind, coastal flooding and more -- into what they mean for society and ecosystems.

This regional information can be explored in detail in the newly developed Interactive Atlas https://interactive-atlas.ipcc.ch/ as well as regional
fact sheets, the technical summary, and underlying report.

Human influence on the past and future climate "It has been clear
for decades that the Earth's climate is changing, and the role of
human influence on the climate system is undisputed," said Masson-
Delmotte. Yet the new report also reflects major advances in the science
of attribution -- understanding the role of climate change in intensifying specific weather and climate events such as extreme heat waves and heavy rainfall events.

The report also shows that human actions still have the potential
to determine the future course of climate. The evidence is clear that
carbon dioxide (CO2) is the main driver of climate change, even as other greenhouse gases and air pollutants also affect the climate.

"Stabilizing the climate will require strong, rapid, and sustained
reductions in greenhouse gas emissions, and reaching net zero CO2
emissions. Limiting other greenhouse gases and air pollutants, especially methane, could have benefits both for health and the climate," said Zhai.

Climate Change 2021: The Physical Science Basis. Contribution of Working
Group I to the Sixth Assessment Report of the Intergovernmental Panel
on Climate Change The Working Group I report addresses the most updated physical understanding of the climate system and climate change, bringing together the latest advances in climate science, and combining multiple
lines of evidence from paleoclimate, observations, process understanding, global and regional climate simulations.

It shows how and why climate has changed to date, and the improved understanding of human influence on a wider range of climate
characteristics, including extreme events. There will be a greater focus
on regional information that can be used for climate risk assessments.

The Summary for Policymakers of the Working Group I contribution to
the Sixth Assessment Report (AR6) as well as additional materials
and information are available at https://www.ipcc.ch/report/ar6/wg1/ ========================================================================== Story Source: Materials provided by Intergovernmental_Panel_on_Climate_Change_(IPCC). Note: Content may be
edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2021/08/210809111125.htm

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