31 March 2014

Impacts of Climate Change Are Widespread and Substantial

In recent decades changes in climate have caused impacts on natural and human systems on all continents and across the oceans, the latest report from the Intergovernmental Panel on Climate Change (IPCC) says.

The report, from the IPCC’s Working Group 2, was released today (31 March) in Yokohama. It describes effects already being seen from changes in climate, the impacts expected for a range of possible future scenarios of greenhouse gas emissions, and ways of managing and reducing risks through adaptation.

Dr Andy Reisinger of The New Zealand Agricultural Greenhouse Gas Research Centre says “The new report summarises why, where and how climate change actually is a serious problem”.

Dr Reisinger jointly led preparation of the chapter on New Zealand and Australia. He says: “Without adaptation, further changes in climate are expected to have substantial impacts on Australia and New Zealand’s water resources, coastal ecosystems, oceans, infrastructure, health and agriculture.”

Key risks identified by the report for New Zealand include increased flooding and wildfire, and coastal damages from sea level rise. Some potential benefits are also identified, such as reduced energy demand for winter heating, and increased spring pasture growth in cooler regions.

The report says that globally, climate change has caused animals and plants to shift their ranges, seasonal activities, migration patterns and abundance.

Changing rainfall or melting snow and ice are affecting water resources and quality in many parts of the world. Negative impacts of climate change on crop yields have been more common than positive impacts. As temperatures rise, so does the risk of severe and pervasive impacts.

Looking to the future, the report concludes that many species and systems are subject to very high risks if global temperatures warm 2°C above recent (1986 to 2005) levels, particularly Arctic sea ice systems and coral reef ecosystems. Sea level rise projected to occur through this century will lead to increasing flooding and erosion impacts for low- lying coastal areas, and some small island states are expected to face very high impacts

For 1°C of warming, climate change related risks are high from extreme events such as heat waves, extreme precipitation (rain and snow), and coastal flooding. Without adaptation, negative impacts for crop production in many tropical and temperate regions are expected for local temperature increases of 2°C or more. The fraction of the global population experiencing water scarcity will increase with the level of warming through the 21stCentury. In the oceans, acidification poses risks especially to polar ecosystems and coral reefs.

Risks of severe impacts on unique and threatened systems including risks of substantial species extinction are high at around 3°C of global warming above 1986 to 2005 levels. High temperature and humidity associated with such temperature rises could compromise normal activities including growing food or working outdoors in some areas for parts of the year.

A first step towards adaptation to future climate change is reducing vulnerability and exposure to present variations in climate. But Dr Reisinger says “ a key challenge for government is to identify when and where adaptation may have to go beyond incremental measures and more transformational changes may be needed, and how to support such decisions”.

Several New Zealand scientists contributed substantially to the report, as well as Dr Reisinger. Professor Alistair Woodward of Auckland University was a Coordinating Lead Author for the Health chapter. Dr Andrew Tait of NIWA and Dr Paul Newton of AgResearch were Lead Authors of the Australasia chapter. Dr Philip Boyd, initially from NIWA and Otago University and now at the University of Tasmania, was a lead author of the chapter on Ocean Systems.

Full text of the “Summary for Policymakers” of the report will be available on the IPCC website (www.ipcc.ch) from 31 March, along with near-final versions of the underlying chapters including the chapter on Australasia.

ENDS

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