Climate science clear – NZ researchers

In the pages of the Dominion Post, New Zealand climate scientists David Wratt, James Renwick and Andy Reisinger  respond to a previous opinion article questioning the science of anthropogenic climate change and the need for action.

Hot sun
Credit: Flickr / Bill Gracey

An excerpt (read in full here):

Human role in climate change is clear

Warming of the climate system is unequivocal, and human influence on the climate system is clear. These are the conclusions from leading scientists around the world, based on a careful assessment of all the relevant climate research, summarised in recent IPCC reports. These findings are very different from the views expressed by the two authors of an opinion article (Hypothetical global warming: scepticism needed, March 5) in the Dominion Post.

That article overlooks a lot of the relevant science, and misconstrues some of it. We don’t expect to change the views of the authors, but we do consider it important that readers are not misled about the factual basis of climate change. Here is some research-based evidence that is relevant to the ten topics raised in the opinion piece.

1. The observed long-term trend in global surface temperature over the past 100 years is clearly upwards. Earth’s surface is now on average about 0.85°C warmer than in the late 19th century. Last year – 2014 -was the warmest year globally since comprehensive records began in about 1880.

The long-term warming trend shows intermittent ups and downs due to natural variations in the exchange of heat with the ocean, volcanic eruptions, and fluctuations in energy from the sun. So periods of slower atmospheric warming are expected from time to time, followed by periods of faster warming. These short-term wiggles don’t change the long-term picture while greenhouse gas concentrations continue to increase.

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