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Global climate change

Key takeaways from the latest IPCC report on the impacts of a 1.5 degree Celsius rise in global temperature

By Brett Anderson, AccuWeather senior meteorologist
10/11/2018, 9:44:57 AM

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The Intergovernmental Panel on Climate Change recently released a new report on the likely impacts from global warming of 1.5 degree Celsius above pre-industrial levels.

The report was prepared by 91 authors and review editors from 40 countries. The report cited over 6,000 scientific references.

--Human activities are projected to have caused ~1.0 degree Celsius of global warming above pre-industrial levels.

--Warming greater than the global annual average is happening in many land regions and seasons (high confidence).

--The Arctic region is warming at a rate of two to three times greater than the rest of the world as sea ice loss continues, and more energy is absorbed into the darker surface waters that are now exposed.

--Man-made emissions, including greenhouse gases and aerosols up to the present are unlikely to cause further warming of more than 0.5 degree Celsius over the next two to three decades (high confidence).

--There is high confidence that global warming is likely to reach 1.5 degree Celsius above pre-industrial levels between 2030 and 2052 if it keeps increasing at its current rate.

--Reaching and sustaining net-zero man-made CO2 emissions and declining net non-radiative forcing would stop man-made global warming on multi-decadal timescales (high confidence).

--By 2100, global sea level rise is projected (medium confidence) to be around 0.1 meter lower with 1.5 degree Celsius warming compared to 2.0 degrees Celsius warming. Regardless, sea level will continue to rise well beyond 2100 (high confidence). The key is the rate of rise. A slower rate of rise will enable greater opportunities for adaptation. A reduction of 0.1 meter in global sea level rise implies that up to 10 million fewer people would be exposed to related risks (medium confidence).

--Increasing warming increases exposure of small islands, low-lying coastal areas and deltas to risks associated with sea level rise for many human and ecological systems, including increased saltwater intrusion, flooding and damage to infrastructure. (high confidence).

--Limiting global warming to 1.5 degree Celsius compared to 2.0 degrees Celsius is projected to reduce increases in ocean temperature and ocean acidity (high confidence). It will also reduce decreases in ocean oxygen levels. All of these are critical to ocean life.

--Temperature extremes on land are projected to warm more than the global mean surface temperature (high confidence). For example, extreme hot days in the mid-latitudes will warm by up to about 3 degrees Celsius at global warming of 1.5 degree Celsius above pre-industrial levels. Extreme hot days in the mid-latitudes will warm by 4 degrees Celsius with global warming of 2.0 degrees Celsius above pre-industrial levels. Extreme cold nights will warm by about 4.5 degrees Celsius with 1.5 degree Celsius of global warming and 6.0 degrees Celsius with 2.0 degrees Celsius of global warming (high confidence).

--The number of hot days is projected to increase in most land regions, with the highest increases in the tropics with 1.5 degree Celsius of global warming (high confidence).

--Of 105,000 species studied, 9 6% of insects, 8% of plants and 4% of vertebrates are projected to lose over half of their climatically determined geographic range for global warming of 1.5° C, compared with 18% of insects, 16% of plants and 8% of vertebrates for global warming of 2° C (medium confidence).

--High latitude tundra and boreal forests are particularly at risk of climate change-induced degradation and loss. Woody shrubs are already encroaching into the tundra.

--With 1.5 degree Celsius of global warming, one sea ice-free Arctic summer is projected per century. With 2 degrees Celsius of warming that increases to at least one sea ice-free Arctic summer per decade (high confidence).

Key quote......

“One of the key messages that comes out very strongly from this report is that we are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice, among other changes,” said Panmao Zhai, Co-Chair of IPCC Working Group I.


The IPCC also posted a FAQ section on the 1.5 degree Celsius goal.

For further information on this newly released report from the IPCC, here is the actual report.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com


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Global climate change