Hundreds of scientists have worked for the last three years to understand just how pressing is the need to limit global warming. The answer – very, very pressing indeed.
Specifically within the next decade, governments and people have to take unprecedented, collective action to limit global warming to 1.5 degree Celsius above pre-industrial (about 200 years ago) temperature.
Scientists and experts from around the world were asked to do so by the UN body on climate change, after the Paris Agreement of 2015.
The report of the Intergovernmental Panel on Climate Change (IPCC) measures the impact of global warming by 1.5 degree versus 2 degree since pre-industrial times.
Speaking to reporters, one of the report’s Indian authors, Aromar Revi, described it as a wake-up call.
The IPCC scientists have concluded that while the effects of a 1.5 degree rise are terrible, it is more acceptable for humans, for other species, for the planet, than the devastation a 2 degree increase will bring.
At current rates, the Earth will be 1.5 degree warmer between 2030 and 2052. That means many of us will be around to see the consequences of our lifestyles, heavily dependent on non-renewables.
The world is already 1 degree hotter. At this level of global warming, India is definitely experiencing climate change, the IPCC scientists say, referring to recent disasters. “People across the world, especially in India, and we can see that in very objective terms, are experiencing the impact of warming. If you take Kedarnath at one end or what happened in Srinagar or Chennai, or recently in Kerala. And of course the very severe drought conditions in many parts of the country. And what we don’t understand is that our ecosystems, on which we survive on land and in the oceans, are experiencing this more severely,” Revi says.
So what difference can half a degree really make?
At 2 degree, no ice in the Arctic Ocean in summer could be a once-in-a-decade phenomenon. At 1.5 degree the chance is a rarer once-a-century.
At 2 degree, virtually all coral reefs (>99%) would be lost; at 1.5˚ the decline would be a little less at 70-90%.
A 2 degree increase would mean extreme hot days in the mid-latitudes – India will be hotter by 4 degree; that comes down to 3 degree if the rise is at 1.5 degree.
The scientists can say with “high confidence” that the number of hot days is projected to increase, more so in the tropics. That’s much of India.
It is a tough ask, the report acknowledges: “The report finds that limiting global warming to 1.5 degree Celsius would require ‘rapid and far-reaching’ transitions in land, energy, industry, buildings, transport, and cities. Global human-caused emissions of carbon dioxide (CO 2) would need to fall by about 45 percent from 2010 levels.”
This should happen by 2030, the report says, reaching ‘net zero’ around 2050. The danger is not just from carbon dioxide but now also from methane, black carbon (soot) and other emissions, it says.
IPCC scientists say we are already experiencing the climate change effects of temperatures one degree higher than about 200 years ago, when the industrial revolution began, riding on coal as the source of energy.
What is uran heat islands?
An uran heat island, or UHI, is a metropoltian that’s a lot warmer than the rural areas surrounding it. Heat is created by energy from all the people, cars, buses, and trains in big cities like New York, Paris, and London. Urban heat islands are created in areas like these: places that have lots of activity and lots of people.
There are many reasons for UHIs. When houses, shops, and industrial buildings are constructed close together, it can create a UHI. Building materials are usually very good at insulating, or holding in heat. This insulation makes the areas around buildings warmer.
“Waste heat” also contributes to a UHI. People and their tools, such as cars and factories, are always burning off energy, whether they’re jogging, driving, or just living their day-to-day lives. The energy people burn off usually escapes in the form of heat. And if there are a lot of people in one area, that’s a lot of heat.