The three theories of the APOCALYPSE: Researchers say pandemics, climate change and nuclear war could wipe out the world unless leaders take action

It is a scene that sparks fear into us all - a catastrophic event occurs, wiping all human life off of the planet.

But experts have warned that it is a terrifying prospect that could soon become a reality. 

They say that the three most pressing risks for humanity are pandemics, extreme climate change, and nuclear war - and that there is a 'dire need' for world leaders to limit the risks of each.

The report carried out by the Future of Humanity Institute (FHI) at Oxford University highlighted the need for more sustained focus on identifying biological weapons. Other existential risks for humanity were pandemics and extreme climate change (stock image) 

THE THREE STEPS TO REDUCING RISKS 

The researchers have laid out three steps that could reduce these risks:

1) Regional and global cooperation in planning for pandemics, and putting more effort into planning for extreme diseases. 

2) Increased attention to the governance of geoengineering research 

3) Recognise the value of preserving humanity's future and reducing existential risks 

The warning comes from a new report, produced by Oxford University.    

The authors called on the international community to recognise the importance of humanity's future and the need to reduce these threats to our existence.

The report was carried out by the Future of Humanity Institute (FHI), which is part of the Faculty of Philosophy at Oxford University.

Researchers interviewed experts in their field and based on these interviews they laid out the key steps that could reduce these existential risks.

Leaders must put more effort into planning for extreme diseases such as ebola and zika, said the report, which was launched at the Finnish Embassy in London.

Emerging diseases pose the biggest problem, since they involve unknown pathogens with no existing vaccinations.

'As the ebola and zika crises showed, managing pandemics is a global responsibility,' says lead author Sebastian Farquhar. 

'But too much planning is still national, and little attention is paid to worst-case scenarios including risks from deliberately engineered pathogens', he added. 

The report said leaders must put more effort into planning for extreme diseases such as Zika and Ebola. The research was presented at the Finnish Embassy in London (stock images)

GLOBAL PANDEMICS 

In 2003, Sars (severe acute respiratory syndrome) – a serious form of pneumonia – spread to six of the world's seven continents within months, infecting an estimated 8,000 people and killing 750.

More recently, ebola – a grisly disease ravaging West Africa with a death toll over 11,000 – threatened to go pandemic in late 2014 after cases seen in travellers arriving back in North America and Europe.

Emerging diseases pose the biggest problem, since they involve unknown pathogens with no existing vaccinations.

The most dangerous are highly contagious but have delayed symptom onset, meaning that infected people unwittingly spread the disease to many others before realising they are sick.

Shape-shifting diseases that mutate fast are almost impossible to vaccinate against. In today's hyper-mobile, city-dominated world, a deadly disease combining these three features could spell doom for the human race. 

The report also highlighted the need for more sustained focus on identifying biological weapons. 

'A recent survey of the views of national technical experts on biological weapons highlighted a dire need for broader and more sustained international focus', said Piers Millett, a biosecurity expert at the Future of Humanity Institute. 

With the power to demolish entire cities in seconds, nuclear bombs are the most devastating weapons on the planet.

Geoengineering, including the release of sulphates in the stratosphere to reduce the planet's temperature, was an important tool for managing the impact of climate change. 

Since the Industrial Revolution, humans have been blamed for upsetting the delicate balance of the atmosphere. 

The authors said we need greater attention to the governance of geoengineering research - currently there is no fit-for-purpose governance framework to manage the risk.

The authors called on the international community to recognise the importance of humanity's future and the need to reduce existential threats. 

Exerts called for international teams to work on managing catastrophic risk and enshrining these commitments into international law (stock image)

They asked for a declaration of responsibility from key global leaders to manage future risks. 

They also proposed building international teams to work on managing catastrophic risk and enshrining these commitments into international law. 

'International cooperation on global risks is more important than ever,' says Sebastian Farquhar, one of the authors of the report.

'Disease, climate change, and nuclear winter don't respect national borders.' 

NUCLEAR WINTER 

With the power to demolish entire cities in seconds, nuclear bombs are the most devastating weapons on the planet.

In many ways, the people annihilated in the first moments of a blast could be considered the lucky ones.

In the 1980s, prominent scientists including Carl Sagan warned that a nuclear war between the US and the Soviet Union could drive the globe into a catastrophic nuclear winter.

Incinerated cities and forests would send heaving clouds of sun-blocking ash into the stratosphere and it could take years for particles to be rained out.

In a worst-case scenario, it is predicted that 99 per cent of the sun's light would be blocked for several months, resulting in noon-time twilight and the halting of photosynthesis, meaning food could become scarce.

Surface temperatures could additionally plummet tens of degrees below normal levels for years or even decades, bringing crippling arctic conditions to the entire globe.

Plants, animals and humans would then perish in the darkness.