How to tackle the climate change crisis is a defining issue of our time.

Its impact is felt globally on the social and environmental pillars of human health – clean air, safe drinking water, sufficient food and secure shelter.

It is estimated the direct damage costs to health will be between $2-4 billion (£1.5-£3bn) a year by 2030.

The areas with weak health infrastructure – mostly in developing countries – will be the least able to cope without assistance to prepare and respond.

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These factors all indicate the dreadful impact that climate change could have on our health unless the global community comes together to negate it.

As a clinician who first specialised in respiratory medicine, then acute medicine, I am concerned that extreme air temperatures could contribute to an ever greater number of mortalities from cardiovascular and respiratory disease across the world.

Elderly people are particularly vulnerable in extreme temperatures.

In the heat wave of summer 2003 in Europe for example, more than 70,000 excess deaths were recorded.

Higher temperatures may also raise the levels of ozone and other pollutants in the air that worsen cardiovascular and respiratory disease.

Furthermore, pollen and other aeroallergen levels are higher in extreme heat.

These can trigger asthma, which affects about 300 million people globally and ongoing temperature increases are expected to increase this burden.

It’s clear that from a clinical perspective, climate change is bad news and will impact our healthcare systems.

We all have an individual responsibility to reduce climate change but our political leaders must be at the forefront of this.

The Paris Agreement came into force in November 2016, which builds on the United Nations Framework Convention on Climate Change.

For the first time all nations were brought into a common cause to combat climate change and adapt to its challenges, with enhanced support to assist developing countries to do so.

As such, it charts a new course in the global climate effort,although America chose to withdraw from the treaty in 2017.

Nonetheless, the College is encouraged the World Health Organisation sees the value of the Paris Agreement as a “health treaty” that attempts to bring down greenhouse emissions to protect the health of people and healthcare systems.

Both the UK Government and the Scottish Government have committed to legally binding targets to reduce their emissions to net zero.

The UK Government has committed to net zero by 2050 while the Scottish Government have committed to do so by 2045.

The Scottish Government has also committed to a new target of reducing emissions by 75 per cent by 2030.

The College welcomes those commitments as part of a global effort to cut emissions, but also because some parts of the UK – particularly our major cities – suffer from poor air quality.

On air quality in particular, a policy supported by the College is low emission zones (LEZ).

In Edinburgh for example, the city council is consulting on the introduction of an LEZ.

The idea is to restrict access for the most polluting vehicles to the city centre and wider city.

This should in turn reduce harmful pollutants including nitrogen oxide (NOx) concentrations.

In line with Scottish Government commitments, Edinburgh is planning for its LEZ scheme to be in place at the end of 2020 and schemes are also scheduled to be introduced in Aberdeen and Glasgow.

In Scotland, we are also eagerly awaiting COP26, the UN Climate Change Conference, which will be in Glasgow from November 9-19.

It is important such events are broad churches and that political and health leaders can learn best practice from one another.

As I reach the end of my presidency of the Royal College of Physicians of Edinburgh, I have chosen to hold a final public lecture – at the college tomorrow - on climate change and its impact on the health of the global population and health care systems across the world.

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I am pleased to welcome three experts with a wealth of experience in this area – Dr Richard Smith, Professor Liz Grant, and Professor David Reay.

Our speakers will discuss the sense of urgency around the climate change crisis and what the health implications are.

I am particularly looking forward to what I’m sure will be a lively debate around the Paris Treaty goals, the level action being taken by government in the UK and Scotland, and COP26.

I would encourage anybody who is interested in the future sustainability of our health systems and our environment to come along, and settle in for a fascinating evening.

The event begins at 6pm tomorrow. To book go to Professor

Derek Bell OBE is president of the Royal College of Physicians of Edinburgh.