Last year was globally the hottest year yet and if the trend continues, there could be disastrous consequences for Australia.
Climate Council climate scientist Professor Will Steffen said the heatwaves could get worse, bushfires would become more extreme, and weather events we see once a century could start happening once a month, if the temperature continues to rise.
The Climate Council released a report on Thursday claiming that 2016 was the hottest year on earth, a record that has now been smashed for three years in a row.
Climate scientists say the global temperature is now 1.2C higher than the pre-industrial temperature.
It doesn’t sound like much, but the global temperature isn’t like the daily temperature you look at on your weather app.
“Go back to the last ice age, 20,000 years ago. Australia was much colder, drier and windier,” Prof Steffen said.
“People would say it felt 20 degrees colder in Australia, but the global temperature has only risen 4C since then.
“It’s like your body temperature, it’s highly complex and if you get a bad fever you won’t live long unless you get it under control.”
At a climate change summit in Paris last year, politicians from around the world gathered to discuss how they would tackle the issue.
Prof Steffen said they agreed the global temperature wouldn’t get to 1.5C warmer than pre-industrial times, but he believes we are scarily close to hitting that number.
That means, in the next century, the world could reach tipping point.
Prof Steffen said if the global temperature rose another 4C, like it has since the ice age, then we would lose all the ice in the northern hemisphere in just 100 years’ time.
He said Greenland would be gone as would the North Pole.
Antarctica would also lose a lot of ice and only a big lonely block would be left in the middle.
Prof Steffen predicted the sea level could rise anywhere from 20 to 40 metres higher than today, which would wipe out most coastal cities around the world.
Prof Steffen said the new Climate Council report showed there was a sense of urgency to start lowering emissions.
“If we keep going on the same trend the world is heading in, heatwaves are going to get a lot worse, we’ll see 40C a lot more often in capital cities and hot days will start earlier in the season and last longer. We’re going to have to cope with that somehow,” Prof Steffen said.
“The sea level could rise, meaning there’d be flooding events in Sydney and Melbourne and places that are flood prone could be unliveable.”
Prof Steffen hopes the report revealing the global temperature rise would put pressure on citizens of countries around the world to change their ways.
“Particularly in Australia where the government is lagging behind what other countries are doing,” he said.
“This issue, though long-term, is extremely important. The decisions we make now will affect the world and our children and grandchildren will live in this. It isn’t something you put aside for the next generation, we have to do it now.”
Climate change could bleach most coral reefs within the century
The Great Barrier Reef's massive loss to coral bleaching last year might have been just a taste of things to come. According to a study by a team of marine scientists, 99 percent of the world's coral reefs could undergo severe coral bleaching before the century ends. The culprit? Climate change. When sea water in a certain location turns warmer than usual, corals in that area expel the algae living in their tissues, effectively turning them white. That's what bleaching is. It doesn't instantly kill the corals, but it makes them much more vulnerable to fatal diseases.
The researchers believe coral reefs around the globe will start going through annual severe bleaching by mid-2050s. Since reefs serve as whole ecosystems, their deaths will also kill a lot of other organisms. In their paper, the scientists call for "adaptive resilience-based management of reefs," which involve "shaping human-environment interactions through management actions that reduce sensitivity to climate threats." In other words, there's really no solution other than to do what we can to mitigate the impacts of climate change. You can read the scientists' study that's backed by UN Environment, World Wildlife Fund and the University of Miami on Nature.
Testing how species respond to climate change
Predicting how species will respond to climate change is a critical part of efforts to prevent widespread climate-driven extinction, or to predict its consequences for ecosystems.
Usually, the current climatic range of a species is used to predict where it will occur under future climate change scenarios.
However, this approach overlooks two important factors that may affect species' responses to climate change:
Species may be able to change the climatic range they can inhabit through evolution
Species within an ecological community may respond differently to climate change, meaning the competitors, predators, pathogens and parasites that a given species encounters under the new climatic conditions may also change.
In a new study, published in Global Change Biology, scientists from the Universities of Bristol, James Cook University, and Melbourne University in Australia tested the response of the tropical rainforest fly Drosophila birchii to a changing climate by transplanting flies in hundreds of cages along mountain gradients in north-eastern Australia, and measuring their reproductive success at different elevations.
Mountains are useful for exploring the effects of climate change because they show predictable changes in temperature and humidity with elevation: In general, sites at low elevations are warmer and drier than higher elevation sites.
By testing the success of many D. birchii families transplanted along elevation gradients, the team were able to measure genetic variation in responses to the thermal environment, which indicates the potential for thermal tolerances to evolve. They found that all families showed similar responses, indicating low levels of genetic variation in temperature sensitivity, and therefore little potential for climatic tolerances to evolve.
The team also compared the response of flies in cages (which experienced the local temperature and humidity, but not interactions with other species) with the abundance of D. birchii in wild populations at the same sites along mountain gradients (where other species were also present), to test whether interactions among species affect responses to climate change.
The reproductive success of D. birchii in cages was lowest at cold, high elevation sites and increased at warmer sites towards the bottom of mountains. Of particular interest however, was that the change in abundance of D. birchii in wild populations along mountain gradients differed from that of D. birchii success in cages. D. birchii was most common at intermediate elevations, with abundance declining at colder sites towards the summit, but also at warmer sites towards the bottom of mountains, where flies in cages thrived.
This suggests that different factors restrict the distribution of D. birchii at either end of its range. Low temperatures prevent expansion of D. birchii at higher elevations, whereas it appears that other species, which were absent from the transplant cages, limit the spread of D. birchii into warmer sites in nature.
Understanding how interactions among species in ecological communities will change as a consequence of climate change is a critical part of predicting the consequences for ecosystem function, and will be a focus of the team's future work.