The train-wreck journey from 2 C to 4 C average rise in global temperature

At 2C, the ice sheets will begin their collapse, bringing, over centuries, 50 metres of sea-level rise. 

An additional 400 million people will suffer from water scarcity, major cities in the equatorial band of the planet will become unlivable, and even in the northern latitudes heatwaves will kill thousands each summer. 

There would be 32 times as many extreme heatwaves in India, and each would last five times as long, exposing 93 times more people. This is our best-case scenario. 

At 3C, southern Europe would be in permanent drought, and the average drought in Central America would last 19 months longer. 

In northern Africa, the figure is 60 months longer: five years. 

At 4C, there would be 8m more cases of dengue fever each year in Latin America alone and close to annual global food crises. 

Damages from river flooding would grow thirty-fold in Bangladesh, twenty-fold in India, and as much as sixty-fold in the UK. 

Globally, damages from climate-driven natural disasters could pass $600tn – more than twice the wealth that exists in the world today. Conflict and warfare could double.

Sea-level rise and deforestation - what are we doing to cope ?

Sea-level Rise

Over the past 20 years, sea levels have risen by 5-6 cm on the Konkan coast, just North of Mumbai. A 5-6 cm rise has led to the ingress of sea water up to 1 km inland, eroding beaches, harming mangroves and coconut and cashew plantations. So it can be imagined what impact the estiamted 90 cms of sea-level rise will have by 2100 - Nearly 40% of Mumbai could be under water. The Indian subcontinent is likely to lose 14,000 sq km of land if sea level rises by a meter. 

The standard response of the authorities only when the situation gets too serious is to construct bunds to keep the sea at bay. These cost as much as Rs 60,000 per metre and are only built at certain stretches.

In India, almost 40 million people will be at risk from sea-level rise by 2050, according to a UN report, with people in Mumbai and Kolkata at higher risk. Experts believe that given this increasing risk, coastal cities must prepare for such eventualities. Evacuation plans should be put in place. In 2005, no Mumbaikar could access higher ground because the roads and railway tracks were under water. Boats, which could have worked, were not provided for rescue or relief.

Deforestation has led to less rain

Analysis of rainfall amount during different seasons indicates decreasing tendency in the summer monsoon rainfall, and increasing trend in the rainfall during pre-monsoon and post-monsoon months. This impacts the present cropping patterns - for example, the pre-monsoon showers in April and May 2018 have caused heavy losses to farmers. 

A study found that forests in north and northeast India contributed significantly towards rainfall through recycled precipitation. Thick vegetation holds moisture well, this evaporates and comes back as rain. Large amounts of trees have been cut in these regions to make way for crops. The study found that large-scale deforestation is responsible for the declining rainfall in the Gangetic plain, Northeast India, and Central India. 

Studies say that overall crop yields could decrease up to 30% in South Asia by the middle of this century.