Climate change challenges the survival of fish across the world

Fish species in many river systems, including the John Day River pictured, will face the challenge of coping with warmer waters in the future. Credit: University of Washington

Climate change will force many amphibians, mammals and birds to move to cooler areas outside their normal ranges, provided they can find space and a clear trajectory among our urban developments and growing cities.

But what are the chances for fish to survive as climate change continues to warm waters around the world?

University of Washington researchers are tackling this question in the first analysis of how vulnerable the world's freshwater and marine fishes are to climate change. Their paper, appearing online Sept. 11 in Nature Climate Change, used physiological data to predict how nearly 3,000 fish species living in oceans and rivers will respond to warming water temperatures in different regions.

"Climate change is happening. We need tools to try to identify areas that are going to be the most at risk and try to develop plans to conserve these areas," said lead author Lise Comte, a postdoctoral researcher in the UW's School of Aquatic and Fishery Sciences. "It's important to look at the organisms themselves as we cannot just assume they will all be equally sensitive to these changes."

Climate Change

The effects of urbanization and climate change are converging in dangerous ways. Cities are major contributors to climate change: although they cover less than 2 per cent of the earth’s surface, cities consume 78 per cent of the world’s energy and produce more than 60% of all carbon dioxide and significant amounts of other greenhouse gas emissions, mainly through energy generation, vehicles, industry, and biomass use. At the same time, cities and towns are heavily vulnerable to climate change. Hundreds of millions of people in urban areas across the world will be affected by rising sea levels, increased precipitation, inland floods, more frequent and stronger cyclones and storms, and periods of more extreme heat and cold.

Climate Change Causes Habitat Loss and Species Extinction

Each species evolves to thrive in its own particular ecological niche – to live in a particular "home" with specific living conditions (including temperatures ranges and other plant and animal species). Some species are more adaptable than others. For example, rats and dogs can survive under many different conditions, but koalas can only live where there is eucalyptus, and pandas where there are bamboo. Human-caused climate change will alter temperatures, precipitation and sea level – wiping out some habitats and shifting others faster than many species can migrate.

A polar bear walks along the edge of 'the ice bridge' in the Robeson channel, near the border between Greenland and Canada. Polar bears are facing extinction as they are losing vast areas of their sea ice habitat due to global warming. 06/28/2009 © Nick Cobbing / Greenpeace

Unless we drastically reduce our greenhouse gas emissions, we can expect several factors to combine that will make the coming die out astonishingly severe. The climate is changing faster than at almost any time in our plane's history. Also, many ecosystems are already stressed by human activities – destructive logging, excessive grazing, over fishing, toxic pollution and the like. And expanding human development destroys habitats and impedes many species from migrating – superhighways effectively block land animals, for example.

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Climate Initiative

Climate Initiative

There is unprecedented, international support to address climate change. The Paris Agreement – a global and legally binding agreement to reduce greenhouse gas emissions to limit global warming to well below 2oC is now in force. The Sustainable Development Goals provide clear 2030 goals on a range of environmental and social issues – including Goal 13 which is an explicit requirement to combat climate change. And recently, the international community reached two more milestone agreements, one on limiting international carbon emissions from aviation, and one on reducing HFCs – one of the more potent greenhouse gases. The challenge is now to ensure business, governments and civil society work together to deliver on the existing commitments ahead of the first review period in 2018.

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