Global Warming

 

As it turns out, potentially a lot. Limiting average global temperature rise to below 1.5 degrees above pre-industrial levels by the end of this century was the aspirational goal adopted in the Paris Agreement of 2015 with the actionable target being set at 2 degrees Celsius. But a review of country pledges and their impact showed that the world was not going to come anywhere close to meeting the 2-degree objective. Cut to the recently-concluded COP26 meet in Glasgow and world leaders were urged to commit to unprecedented steps for aggressively chasing the 1.5-degree goal.

How Much Hotter Is The Earth Already?

Ahead of the COP26 meet, the UN’s Intergovernmental Panel on Climate Change (IPCC) had warned that while emissions cut would need to range between 25-45 per cent globally by 2030 over 2010 levels if the world were to achieve the Paris temperature target, what countries have cumulatively pledged would only cut greenhouse gasses back by around 12 per cent. Failure to check emissions, it had said, had put the planet on course for a temperature rise of about 2.7 degrees Celsius by the end of this century.

The voluntary Paris Agreement goals — the so-called nationally determined contributions (NDCs) — were up for their first five-yearly review at Glasgow, where countries were obligated to step up on their climate targets. The new pledges made, the International Energy Agency has said, could hold warming to below 1.8 degrees Celsius although that view has been met with some amount of scepticism.

Experts say that the world has so far heated up to around 1.1 degrees Celsius above pre-industrial levels. In fact, each of the last four decades was hotter than any decade since 1850.

The tough solution proposed at COP26 for pulling the planet back from the brink of devastating climate change was for halving global CO2 emissions by 2030 from 2010 levels and hitting the net zero target by 2050. Net zero means that any emissions produced would be cancelled out by increasing the global green cover or using advanced technologies to suck CO2 out of the air and storing it away.

What Happens With 0.5 Degrees Of Extra Warming?

The clear and present danger that is climate change, experts say, is manifested in the increasing frequency of extreme weather events the kind of which has hitherto been virtually unknown. Like soaring temperatures in the Pacific Northwest, floods earlier this year in Germany and other parts of Europe and melting of the Siberian permafrost.

Studies say that even if we manage to peg average global temperature rise to the 1.5-degree target, about 14 per cent of the world’s population would still be exposed to extreme heat waves once every five years. Fail that target and inch up to 2 degrees and the proportion of people jumps to 37 per cent.

As experts have pointed out, the 1.5-degree target is for an average rise of the temperature globally, the truth is that some places have already seen more heating than that. In fact, it has been pointed out that between 20-40 per cent of the world’s people live in areas that experienced warming of more than 1.5 degrees in at least one season between 2006-2015.

As Nasa points out, citing the IPCC Special Report on Global Warming of 1.5 Degrees Celsius of 2018, “temperatures increase at different speeds everywhere, with warming generally higher over land areas than oceans. The strongest warming is happening in the Arctic during its cool seasons, and in Earth’s mid-latitude regions during the warm season".

How Will Excess Warming Affect Places With Hot Climate?

Global warming means land areas across the globe will see more hot days, but the effect will be especially pronounced in the tropics.

The Nasa report said that the hottest days in the mid-latitudes will be up to 3 degrees Celsius hotter at 1.5 degrees of warming and up to 4 degrees hotter at 2 degrees. Central and Eastern North America, Central and Southern Europe, the Mediterranean, Western and Central Asia and Southern Africa will see the warmest extreme temperatures with longer warm spells forecast to affect many densely populated regions.

At 1.5 degrees, twice as many megacities as today are likely to become heat stressed, the report said, adding that 2 degrees could mean India and Pakistan may experience annually the deadly heatwaves they had witnessed in 2015.

Stressing how no action was too much in the fight to protect the climate, the COP26 organisers had said that the “commitment to aim for 1.5 degrees is important because

every fraction of a degree of warming results in the tragedy of many more lives lost and livelihoods damaged".

What Impact Will Climate Change Have In Cold Places?

In the colder latitudes, even the chilliest night will be about 4.5 degrees Celsius warmer when global warming averages at 1.5 degrees while the temperatures could be warmer by about 6 degrees at 2 degrees. The duration of the cold season will generally be shorter, Nasa said.

Land areas inside the Arctic circle, too, will be less freezing on their coldest days by as much as 5.5 degrees at 1.5 degrees any by 8 degrees at warming of between 1.5 and 2 degrees.

“At 1.5 degrees, there’s a good chance we can prevent most of the Greenland and west Antarctic ice sheet from collapsing," climate scientist Michael Mann of the Pennsylvania State University told news agency Reuters. But if the temperature rise is above 2 degrees, the polar ice sheets could collapse, which would trigger sea-level rise of up to 10 metres.

What’s The Risk Due To Warming Oceans For Islands?

The IPCC report says that even when the mercury stays per target at 1.5 degrees of warming, sea levels will see a rise. Such rise though is estimated to be 0.33 feet lower at 1.5 degrees Celsius of warming than at 2 degrees. At 2 degrees, the report says, more than two-thirds of Earth’s coastlines will see sea-level rise greater than 0.66 feet. That would trigger increased coastal flooding, beach erosion, salinisation of water supplies, etc.

If the world succeeds in keeping global temperature rise to no more than 1.5 degrees, it would mean 10.4 million more people will be spared these impacts by 2100. The IPCC report said that risks associated with sea-level rise are projected to be the highest in South and Southeast Asia.

The Union Ministry of Science and Technology has referred to a study that says sea-level rise around the Lakshadweep Islands would range between 0.4 mm/year to 0.9 mm/year. It found that while the smaller islands are expected to have major land-loss, the larger islands of Minicoy and the capital Kavaratti are also vulnerable to sea-level rise, and expected to experience land-loss along 60 per cent of the existing shoreline.

Will Rising Global Temperatures Bring More Rain, Droughts?

As the planet heats up, there is a heightened risk of droughts and water stress. But, IPCC says, limiting warming to 1.5 degrees can significantly reduce the chance of water crisis in regions like the Mediterranean, Southern Africa, South America and Australia. About 61 million more people living in urban areas across the globe could face severe drought in a 2-degree Celsius warmer world.

But not just droughts and dry weather, global warming of 2 degrees will also drive a rise in in heavy rainfall events compared to at 1.5 degrees warming in places in the Northern Hemisphere, Northern Europe, the Tibetan Plateau, Southeast Asia. These areas may see increased flooding. IPCC says that heavy rainfall from tropical cyclones is also projected to be higher.

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