This doesn’t stop people from believing I owe them a debate - I was recently labelled an “absolute innocent dupe” by one delightful chap who had messaged me asking for a “chat” - on Christmas Eve, no less. Meanwhile, out in the real world, people are in no doubt about the existence of climate change because they are living through it. I have just returned from a two-week holiday in Tasmania with my family. One of the national park rangers on the Tasman Peninsula told us how 15 years ago he was a fisherman operating near Fortescue Bay catching a variety of fish including barracuda. In the past 12 years most of the fish have disappeared because of habitat destruction - a 2 Celsius rise in the average seawater temperature has killed most of the giant kelp forest, which had provided the breeding grounds for many of the fish species. Sea urchins washed down from NSW were eating the remaining species of kelp and the sea temperature was now warm enough for them to breed in Tasmanian waters.

The East Australian Current - made famous by the Pixar movie Finding Nemo - used to stop near Eden on the NSW south coast but now went past Tasman Island. This brought down the tropical fish from the Great Barrier Reef but as soon as the currents shifted and cold water came up from Antarctica, the fish died. This year was particularly bad but our ranger said he’d been seeing dead tropical fish wash up on beaches for the past four or five years. Marlin and Dory riding the turtles along the East Australian Current in Finding Nemo. Credit:Disney-Pixar The ranger also talked about the impact on the community. Many young locals had grown up expecting to join the family fishing business, but that future had been ripped away from them. The lucky few had found work taking tourists out to see the sea cliffs and wild seals. There are far fewer fishing boats in Fortescue Bay these days and those that remain are often targeting species like kingfish that were never previously found in Tasmania. This isn’t a case of a guide telling tall stories to entertain the punters - research from the University of Tasmania verifies his account. Adding the shift in the East Australian Current to the backdrop of global ocean warming means Tasmanian waters are warming four times faster than the rest of the world.

The giant kelp forest is 95 per cent gone due to warming waters and researchers are studying remnant giant kelp to see if it can be rehabilitated. As well as the migration of long-spined sea urchins from more northerly states, the warmer waters have also brought diseases that threaten the Tasmanian oyster industry. And a citizen science project called Red Map documenting the spread of species due to climate change is full of sightings of exotic fish in Tasmania. There are stories like this from all over the world - the specifics change, but the broad themes are constant. Discussions about climate change can be abstract at the planetary level, but locally it all gets real. It’s a natural human reaction to shy away from the grim reality of what’s happening and what’s in store. It protects us from falling into that most destructive of states: despair. Perhaps that explains climate change denialism to some extent - though I also blame deliberate misinformation from vested interests and attention seekers who've turned the issue into another front of the culture wars.

Loading But denial is not a mainstream view. The 2018 Lowy Institute Poll found 59 per cent of Australians regard climate change as a “serious and pressing problem”, while 84 per cent say the government should focus on renewables even if it requires spending. Climate change was rated a "critical threat" to the nation, with only terrorism and North Korea’s nuclear program ranked higher in the nation’s list of worries. Yet even those of us who accept the science on climate change tend to compartmentalise our fears for the future in order to function day to day. It means we’re living with cognitive dissonance - the mental discomfort or psychological stress that comes from believing two or more contradictory ideas at the same time. This takes a toll on our mental health and leaves us less able to cope with life’s challenges, at the very time we need to be facing up to our problems. The antidote is action.

A number of studies over many years suggest activism and volunteering is one of the best things we can do for our mental health. Happily, it’s also one of the best things we can do for the planet. While most scientists say it’s too late to completely prevent or reverse climate change, they also say we can mitigate the damage and avoid the worst of it. I also advocate getting out and enjoying the beauty of our natural world so that we’re acting from a place of love not fear. This is especially important for parents - let's teach our children to fall in love with the world before we depress them about how broken it is. Let's quit branding people as hypocrites if they call for action on climate change but continue to eat meat or fly on aeroplanes or own a mobile phone. It can be more comfortable to undermine the messenger rather than hear the message, but expecting humans to be perfect is doomed to failure. Acting on climate change is not all or nothing - there’s a vast difference between 1.5C or 4C warming and we need to collectively shift the dial. Arguing with people about whether climate change is real is a dangerous distraction. We just need to get on with doing something about it.