Now, in complex systems, small changes can add up to large effects. The Fifth Assessment Report does take note of extreme weather and climate events and global-scale changes in precipitation patterns witnessed in recent years, citing that each of the last three decades has been successively warmer at the Earth's surface.

The panel finds that the concentrations of carbon dioxide (CO2) and other gases causing the greenhouse effect in the atmosphere have risen 40% since pre-industrial times, mainly due to the higher combustion of fossil fuels. And as rising emission levels will cause further warming, the global community needs to carry out effective mitigation and policy action to arrest climate change.

The sceptics can point out that the rate of warming during the 15-year period, 1998-2012, has been a mere 0.05° C, and so far slower than the trend since 1951. But the report avers that the figures for short periods can be misleading and adds that many of the lately observed changes in climate patterns are unprecedented in decades and millennia.

The contrast between wet and dry seasons and interregional variations are expected to increase, with the water cycle affected. Here, in India, CO2 emissions remain minuscule in per-capita terms, but given that energy poverty is widespread and energy demand likely to greatly increase going forward, we need to rev up energy efficiency and step up supply of alternative, renewable energy sources to boost overall supply and better manage the risks of climate change.

It is entirely possible that in the future, there would be viable scientific solutions for global warming and climate change, and the technoeconomic paradigm based on fossil fuels of today is likely to change. But that possibility is a matter of conscious policy and investment, not chance.