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Think globally, act locally

Will Steffen

· Auckland Climathon

Climathon is an excellent opportunity for Aucklanders to take action on climate change. And the local level is where much of the action is, and ought to be.

Building transformative energy and transport systems, which take carbon out of the equation yet are reliable and affordable, is the heart of the challenge. Auckland has an excellent opportunity to lead the way.

While a focus on local action is indispensable, it is crucial that the global, long-term nature of the climate change challenge remains sharply in focus. Understanding the magnitude and the nature of the challenge can motivate and guide local action.

There is no better way to understand the severity of human-driven climate change than to compare it to the changes in the climate that natural forces have driven in the past.

Global average temperature is currently about 1.1 or 1.2°C above the pre-industrial baseline. That doesn’t sound like much - what does it matter if the high temperature on a summer day in Auckland is 28°C instead of 27°C? That, however, is a misinterpretation of what a 1°C warmer world represents.

Global average temperature is a measure of the state of the climate system as a whole – not the temperature you feel on the ground in Auckland. The global average temperature of the last ice age, when woolly mammoths and sabre-tooth tigers roamed the northern hemisphere and vast ice sheets covered northern Europe and much of central Canada and the USA, was only 4°C lower than pre-industrial. If continued, the present rate of greenhouse gas emissions could drive a temperature rise of 4°C by the end of this century.

The rate at which the global average temperature is rising – 170 times faster than the background rate of change over the past 7,000 years – is striking. This is such a fast rate that many of the Earth’s ecosystems cannot cope. It is no wonder that the Great Barrier Reef has suffered mass bleaching events in two consecutive years and that wildfires are roaring across landscapes in the western USA, Canada and Siberia.

Human emissions of carbon dioxide are creating other stresses for the natural world. Part of the carbon dioxide that we emit into the atmosphere is absorbed by the ocean, where it reacts with water to form carbonic acid. Because of this process, the acidity of the ocean is increasing, at a rate faster than any other over the last 300 million years. Rapidly increasing ocean acidity increases the stress on marine organisms that have calcium carbonate shells or skeletons, such as coral.

It’s also no surprise that many types of extreme weather events are becoming more intense and occurring more frequently. Heatwaves in Europe, drought in parts of New Zealand, bushfires in Australia and hurricanes (tropical cyclones) in the Caribbean region are just a few examples.

And if those impacts aren’t enough, we also face the threat of tipping points in the climate system – points of no return that, once they are crossed, will accelerate global warming even if human emissions are reduced. Some of these tipping points could be breached at temperature rises as low as 1.5 or 2°C above pre-industrial.

Any way you look at it, warming much above 2°C will drive unacceptably high risks by any reasonable assessment. It is easy to get overwhelmed when the real nature of the challenge becomes apparent.

Can we meet the Paris 2°C target?

Yes, but time is running out. Global emissions must peak in the next few years and start heading sharply down by 2020. The good news is that we still have a fighting chance thanks to China. Largely driven by rapid reductions in Chinese emissions over the past few years, global emissions have levelled off over the past three years.

But we need plans, roadmaps, innovative companies and decisive governments that are ready to lead.

Most of all, we need engaged citizens that make it happen. Individual action is great, but the problem will only be solved if we have collective action.

Thinking globally is crucial for powering effective action on climate change – action that is sustained, effective and collective, building from individual cities like Auckland towards truly global solutions.

Will Steffen is Emeritus Professor, Fenner School of Environment & Society, Australian National University. He has a long history in international global change research, and his interests span a broad range within the fields of sustainability and Earth System science.

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