“Climate change in Australia: A lot of hot air or in hot water?”

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Professor Anthony Richardson

School of Mathematics and Physics,

The University of Queensland/CSIRO

Thursday, 10th May, 2018

Richardson1There is a lot of confusion around climate change and a lot of comments from people who know very little about the topic. There seems to be a misguided view that everyone’s opinion is equal when it comes to topics that require a level of expertise and knowledge. When I take my car to the mechanic, I don’t argue with him when he says that the brakes need fixing – I trust his expertise. I don’t think everyone’s opinion is equal when it comes to the safety of my family in the car (certainly not mine, as I know nothing about cars!), and I don’t think everyone’s opinion is equal when it comes to the safety of my family with climate change. Science is not an opinion, but a testable body of knowledge that evolves as we learn more.

In this presentation, I tried to share some of my knowledge about climate change – particularly in my area of expertise which is the current and future impacts of climate change on biodiversity. I started with probably the most compelling evidence showing the increase in carbon dioxide – a time series of carbon dioxide over 800,000 years from atmospheric and ice core measurements produced by NOAA in the US (https://www.youtube.com/watch?v=pVYt9ZDDfBs&t=14s) .

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I then dispel two of the common myths surrounding climate change. The first was that warming is mainly in areas around cities – and that it is an artefact of our temperature measurements predominantly being around these hotspots. I showed that this is false - a movie of temperature on land in the oceans over the past 150 years produced by NASA in the US shows rapid warming everywhere (https://www.youtube.com/watch?v=qNafKlhVRk0). The other myth was that carbon dioxide does not lead to warming, and I showed evidence that over the past 800,000 years, carbon dioxide and temperature are tightly linked.

Climate change is not something happening in the future, but something happening now. I described the impacts of climate change on marine ecosystems that have happened over the past 50 years, particularly drawing on my own research. Data show that seaweeds, corals, marine snails, crabs, phytoplankton, zooplankton, adult fish and young fish are all moving towards the poles (toward cooler water) as the seas are warming (there is insufficient information on sharks). As different species are moving at different rates, there is now a rearrangement of marine communities, with new species interactions (e.g. predators might have to depend on different prey, for example). I showed that coral cover on the Great Barrier Reef is declining, primarily because of coral bleaching (where corals die because it is too warm), high nutrient and sediment runoff (from cities and agriculture), and crown-of-thorns outbreaks. This “triple whammy” is compromising the long-term viability of the Great Barrier Reef.

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I then focused on likely changes until 2100 (when our grandkids are likely to be alive). Continuing on the path of high carbon dioxide emissions that we are now on, the Earth is likely to warmer by about 4°C, and by more than 6°C in the Arctic. This will lead to a massive redistribution of species on Earth as they move poleward to cooler temperatures, and the probable disappearance of many species – particularly those from polar environments. We have simulated the impact of warming on whales (blue, fin, humpback southern right, minke) until 2100. All of them increase in abundance in the first half of this century as they bounce back after harvesting in the 1900s, but then many species, particularly humpback, decline in the second half of this century as warming melts more pack ice in the Southern Ocean and leads to declines in krill, their primary food source.Richardson7

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I then conclude highlighting the probable impact of climate change in southeast Queensland - not my area of expertise ;-) The latest research shows that climate models are generally predicting a modest decline in rainfall in the region. Of concern is the increase in heatwaves in southeast Queensland. On our current emission pathway, the number of days above 35°C is likely to increase at Brisbane Airport from 1 per year to 6 by 2070, at Tewantin from 3 to 11, and at Amberley from 12 to 41. This will not only place immense stress on the natural environment to cope with these changes, but also us. Scientists say that to keep warming below 1.5°C, humanity has to ask decisively to reduce emissions within the next decade. We now have enough information about the likely future if we maintain our present path, so it is up to us to act now if we want a different future for our kids.