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A 0.5°C difference in global temperature change can significantly impact water systems and human health. Climate change is already affecting both the availability and quality of water resources. On a warming planet, extreme and irregular weather events such as floods and drought are expected to become more frequent. Warmer river and lake temperatures will reduce dissolved oxygen in the water, and make habitats more lethal for fish. Warming waters are also more prolific incubators of harmful algae and cyanobacteria that are toxic both for aquatic life and for humans. The Intergovernmental Panel on Climate Change’s Special Report on Global Warming of 1.5°C, published in late 2018, noted that by limiting the global average temperature increase to 1.5°C above pre-industrial levels, instead of 2°C, we could significantly reduce the risk of severe negative outcomes for ecosystems and human development. If the temperature increase was limited to 1.5°C, sea level rise by the year 2100 would be 10 centimetres lower than it would be at a 2°C increase - posing less of a threat to coastal cities, while also reducing the risk of severe heat waves like those that swept across Europe, China, the US, and India in 2022. Just a half-degree of warming above 1.5°C would also mean a ten-fold increase in ice-free summers in the Arctic, and a doubling of the rate of crop loss, according to the IPCC report - which identified important links between climate change and safe drinking water access, and cautioned that socio-economic factors like governance and wealth play significant, related roles. Tropical forests, ocean systems and corals, and wetlands are particularly vulnerable. More extreme variations in rainfall and drought are likely in both a 1.5°C and 2°C warming scenario; in many cases, more warmth will lessen the quality and quantity of water for agriculture and other human activity. Limiting warming to 1.5°C will be difficult, but it remains possible, according to the IPCC - which also indicated that breakthroughs in carbon-sequestration technology may be necessary to complement existing emissions-reduction efforts. Emerging technologies and adaptation can both help reduce vulnerability to climate change, and increase the resilience of water resources and systems. Further research is needed in order to increase awareness and understanding of climate change generally, and to better adapt.

Water, Climate Change and Ecosystems

KEY TRENDS

Clean Water and Sanitation