JOIN USExtreme or abnormal climate-related events are occurring around the globe and even in India with unprecedented of ferocity. India experienced many extreme events recently, Hudhud cyclone in the coastal Andhra Pradesh, the unprecedented rain and floods in Jammu and Kashmir, the cloudburst in Uttarakhand, and the list goes on. Changes in rainfall patterns such as drought, excessive rainfall, early or late arrival of monsoons and rainfall at unusual periods are becoming common. Ordinary people are forced to ask if all such abnormal events are caused by global warming or climate change.
In this context, Inter-governmental Panel on Climate Change (IPCC), a scientific body, was established in 1988 under the auspices of the UN with 195 member countries. The IPCC periodically assesses the most recent scientific, technical and socio-economic information. It was awarded the Nobel Prize in 2007.
The latest assessment of climate change released by the UN Secretary General on November 2 in Copenhagen involved 830 scientists from over 80 countries who assessed over 30,000 scientific papers. Only a few of the key highlights of the IPCC assessments presented there and IPCC does not provide information at country or state level, due to limited modelling or observational scientific studies, especially from regions such as India.
Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes in weather patterns are unprecedented. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished and sea level has risen. Each of the last three decades has been successively warmer than any preceding decade since 1850. The ocean has absorbed about 30 per cent of the emitted Carbon dioxide (CO2) causing ocean acidification. The Greenland and Antarctic ice sheets have been losing mass flooding the oceans. Over the period 1901–2010, global mean sea level rose by 0.19 metre.
In recent decades, changes in climate have caused impacts on nature (forests, oceans, rivers, etc) and human settlements (agriculture and coastal). In many regions, changing precipitation or melting snow and ice are altering hydrological systems, affecting water resources in terms of quantity and quality. Many forest, grassland, freshwater, and marine species have shifted their geographic ranges, seasonal activities, migration patterns, abundances, and species interactions in response to ongoing climate change. Negative impact of observed climate change on crop yields is recorded.
Thus, the main message is that climate change is not a distant phenomenon, but it is already happening now and impacting rainfall patterns, food production, biodiversity, fish availability, water resources, etc not noticed by us.
Continued emission of greenhouse gases (CO2, methane, and Nitrous Oxide), caused by use of coal and natural gas for electricity generation, diesel, petrol, and deforestation, etc., will cause further warming and long-lasting changes in climate system namely, rainfall patterns, floods, droughts, cyclones, hurricanes, with severe, pervasive and irreversible impacts for people and ecosystems. What is of consequence is some of the impacts such as sea level rise and biodiversity loss are irreversible.
The IPCC largely provides global level climate change assessments. According to a modelling study by Indian Institute of Science, India could experience additional warming of 1.5 to 3 degrees C by as early as 2030s and cross a catastrophic level of 4 to 6 degrees C by 2080s. Further, the rainfall may increase in large parts of India, which is not good news since the number of high rainfall events are projected to lead to floods. The governments under the UN framework, based on scientific evidence, have agreed that 1.5 to 2 degrees C warming over pre-industrial level is dangerous and aim to stabilise warming at that level.
Climate change is projected to undermine food production and security, for regions such as India. For wheat, rice, and maize in tropical regions, climate change is projected to negatively impact production for local temperature increases of 2 degrees C or more above late-20th century levels.
Global temperature increases of about 4 degrees C or more above late-20th century levels, combined with increasing food demand, would pose large risks to food security in India and globally. Climate change is projected to reduce surface water and groundwater resources intensifying competition for water. Thus in India, climate change will aggravate the crisis in agriculture resulting from water scarcity, decline in ground water level, soil erosion, land degradation, and excessive dependence on monsoon.
Plant and animal species
A large fraction of plant and animal species face increased extinction risk due to climate change during the 21st century. Most plant species cannot naturally shift or migrate their geographical ranges sufficiently fast to keep up with current and high projected rates of climate change.
In urban areas, climate change is projected to increase risks for people, assets, and ecosystems, including risks from heat stress, storms and extreme precipitation, coastal flooding, landslides, drought, water scarcity, sea-level rise, and storm surges. These risks are amplified for cities like Bangalore lacking in essential infrastructure and services.
Aggregate economic losses accelerate with increasing temperature and from a poverty perspective, climate change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security. Climate change is projected to increase displacement of people leading to migration within and across countries such as from Bangladesh. Climate change can indirectly increase risks of violent conflicts by amplifying well-documented drivers of these conflicts such as poverty and economic shocks.
The IPCC provides solutions to address climate change. The governments at the global, national and state levels are yet to realise the severity of climate change and the and time is running out. The humanity is on the threshold of unprecedented changes affecting every sphere of human life and nature.
(The writer is professor at the Indian Institute of Science, Bangalore and author of IPCC reports)