In China, more than 900 million people have been subject to an unprecedented heatwave lasting more than 70 days. In recent months, records have also been broken in many parts of Europe and the UK.

India suffered its hottest March in more than a century, and in mid-June, nearly one-third of the US population were under a heat alert.

Australians too are no strangers to record-breaking heat. We have experienced nine of the 10 hottest years since 2005, with 2019 being the hottest on record.

As an emergency doctor, I already see the direct impact increasing temperatures has on patients - including some of the most vulnerable members of our community.

I'm deeply concerned about the threat that rising global heat poses to the health of Australians and to our already stretched hospitals.

New research out last week has only heightened my concerns. A paper from Harvard and Washington universities suggests that greenhouse gasses from human activity could further drive extreme temperatures in the coming decades, even if global warming is limited to 2 degrees in line with the Paris Agreement: "for many places close to the equator, by 2100 more than half the year will be a challenge to work outside...".

If emissions remain unchecked until 2100, the research further states, "extremely dangerous" conditions, in which people should not be outdoors for any length of time, could become common in countries closer to the equator.

The message is clear: while humans have locked in a rise in heat, we have the capacity to make the future a habitable place: if we act now with the urgency that this challenge demands. At stake are the lives and wellbeing of billions of children born today in the world's tropical and sub-tropical areas, including those in much of Australia.

As temperatures increase, so will incidences of heat stress.

Many people will think of heat stroke - the physiological state that results when the body's cooling mechanisms can no longer manage and the body's temperature soars to dangerous levels, such as marathon runners.

But heat stroke is just part of the picture.

There is increasing evidence that heat stress can affect all organs of the body. A recent study by James Cook University found "hospital admissions for cardiovascular, renal, respiratory, mental and behavioural conditions increased during heatwaves".

I know from my experience working in an already overcrowded and busy emergency department that heat waves worsen presentations across the board.

We may see a few athletes with heat stroke competing in a triathlon, but also the elderly, people outdoors fainting, kids feeling dizzy, patients on blood pressure medications having falls because they've become dehydrated.

Extreme heat will increase the demand on the health system. More ambulance call outs, more presentations at emergency departments, more hospital admissions. We may need more staff and beds, while infrastructure including power sources may be affected.

How many more "unprecedented" extreme weather events do we need to have before we see real action and preparedness on climate change?

The current federal government's commitment of 43 per cent reduction in emissions by 2030 shows some progress, but this goal should be seen as a starting point. The government must establish a review and ratchet mechanism as part of legislation to ensure that we keep to the Paris Agreement aimed at limiting global warming to 1.5 degrees.

Central to Australia's capacity to do our fair share of the heavy lifting to curb climate change, is the need to address the fossil fuel industry and its relentless greenwashing, disinformation and fear campaign to protect its interests.

As we did with the tobacco industry, we cannot allow this sector to jeopardise our health and our future. The science clearly states that coal, gas and oil must stay in the ground. Now is the time for leadership that will transition our economy from these polluting fuels, and do this in a way that prepares workers and communities in these industries for good jobs in solar, wind and other renewables that Australia is so richly endowed with.

The government must also develop a national climate change and health strategy to build resilience in the healthcare system to ensure healthcare can continue to reliably provide vital services in response to climate change fuelled disruptions such as heatwaves.

This is the critical decade for action on climate change. We owe it to ourselves and our families, and we owe it to our young people and their children.