Wednesday 28 October, 2020

UN: World could hit 1.5-degree warming threshold in 5 years

Photo via iStock

Photo via iStock

The world could see average global temperatures 1.5 degrees Celsius (2.7 Fahrenheit) above the pre-industrial average for the first time in the coming five years, the UN weather agency said Thursday.

The 1.5-C mark is the level to which countries have agreed to try to limit global warming. Scientists say average temperatures around the world are already at least 1 C higher now than during the period from 1850-1900 because of man-made greenhouse emissions.

The World Meteorological Organization said there is a 20 percent chance that the 1.5 C level will be reached in at least one year between 2020 and 2024.

The period is expected to see annual average temperatures that are 0.91 C to 1.59 C higher than pre-industrial averages.

The forecast is contained in an annual climate outlook, spearheaded by the United Kingdom's Met Office.

WMO chief Petteri Taalas said the study shows "the enormous challenge" countries face in meeting the goals of the 2015 Paris accord.

The agreement sets a goal of keeping global warming well below 2 degrees Celsius (3.6 Fahrenheit), ideally no more than 1.5 C.

The agency noted that the models used for the forecast don't consider the impact that the coronavirus pandemic might have on reducing emissions of planet-warming gases such as carbon dioxide.

"The industrial and economic slowdown from COVID-19 is not a substitute for sustained and coordinated climate action," Taalas said.

"Due to the very long lifetime of CO2 in the atmosphere, the impact of the drop in emissions this year is not expected to lead to a reduction of CO2 atmospheric concentrations which are driving global temperature increases," he said.


What difference does a degree make?

According to NASA's Global Climate Change website, there are many life-threatening outcomes of a global temperature increase:

1. Threatens turtle population growth

'A few degrees make a huge difference. At sand temperatures of 31.1 degrees Celsius (88 degrees Fahrenheit), only female green sea turtles hatch, while at 27.8 degrees Celsius (82 degrees Fahrenheit) and below, only males hatch.

More females and less male turtles can affect numbers of already threatened species like Leatherback, Green, Loggerhead and Hawksbill turtles.


2. Threatens water availability

By limiting global warming to 1.5 degrees Celsius, up to half as many people around the planet may experience water stress caused by climate change, depending on future socioeconomic conditions.

The degree will vary from region to region. People in river basins, especially in the Middle and Near East, will be particularly vulnerable.


3. Extreme weather/flooding events

At 2 degrees Celsius warming, some places will see an increase in heavy rainfall events compared to at 1.5 degrees warming.

This includes Eastern North America, which will see higher flooding risks.

Other affected areas include the Northern Hemisphere high latitudes (Alaska/Western Canada, Eastern Canada/Greenland/Iceland, Northern Europe, Northern Asia) and Southeast Asia.


4. Deforestation

Warming of 1.5 to 2 degrees Celsius will lead to a reduction of rainforest biomass and will increase deforestation and wildfires. Trees at the southern boundaries of boreal forests will die.


5. Sea-level rise

Island nations are at increased risk: The IPCC Special Report states, with medium confidence, that at an increased level of warming between 1.5 and 2 degrees Celsius, instabilities in the Antarctic ice sheet and/or the irreversible loss of the Greenland ice sheet could lead to multi-meter (greater than 6 feet) sea level rise over a time scale of hundreds to thousands of years.


6. Coral reefs at risk

Ocean warming, acidification and more intense storms will cause coral reefs to decline by 70 to 90 percent at 1.5 degrees Celsius warming, becoming all but non-existent at 2 degrees warming.


7. Human illness

The risk of heat-related illness and death will be lower at 1.5 degrees Celsius warming than at 2 degrees. Cities will experience the worst impacts of heatwaves due to the urban heat island effect, which keeps them warmer than surrounding rural areas.

More people will die from vector-borne diseases like malaria and dengue fever, with risks increasing more at 2 degrees warming, according to the report.


8. Less food

Food security is expected to be reduced at 2 degrees Celsius warming compared to 1.5 degrees, say the report authors, with the largest risks emerging in the African Sahel, the Mediterranean, Central Europe, the Amazon, and Western and Southern Africa.

Yields for such crops as maize, rice, wheat and other cereal crops will be smaller at 2 degrees warming than at 1.5 degrees, especially in sub-Saharan Africa, Southeast Asia and Central and South America. For example, global maize crop yields will be about 5 percent lower at 2 degrees warming.

Rice and wheat will become less nutritious.

Projected food availability will be less at 2 degrees Celsius warming than at 1.5 degrees in Southern Africa, the Mediterranean, the Sahel, Central Europe and the Amazon.

Seven to 10 percent of rangeland livestock will be lost at about 2 degrees Celsius warming.

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