Image caption Food security was interwoven with the climate issue, speakers told the conference

Climate change poses "an immediate, growing and grave threat" to health and security around the world, according to an expert conference in London.

Officers in the UK military warned that the price of goods such as fuel is likely to rise as conflict provoked by climate change increases.

A statement from the meeting adds that humanitarian disasters will put more and more strain on military resources.

It asks governments to adopt ambitious targets for curbing greenhouse gases.

The annual UN climate conference opens in about six weeks' time, and the doctors, academics and military experts represented at the meeting (held in the British Medical Association's (BMA) headquarters) argue that developed and developing countries alike need to raise their game.

Scientific studies suggest that the most severe climate impacts will fall on the relatively poor countries of the tropics.

UK military experts pointed out that much of the world's trade moves through such regions, with North America, Western Europe and China among the societies heavily dependent on oil and other imports.

Rear Admiral Neil Morisetti, climate and energy security envoy for the UK Ministry of Defence (MoD), said that conflict in such areas could make it more difficult and expensive to obtain goods on which countries such as Britain rely.

"If there are risks to the trade routes and other areas, then it's food, it's energy," he told BBC News.

"The price of energy will go up - for us, it's [the price of] petrol at the pumps - and goods made in southeast Asia, a lot of which we import."

Coffee climate

A number of recent studies have suggested that climate impacts will make conflict more likely, by increasing competition for scarce but essential resources such as water and food.

The International Institute for Strategic Studies, for example, recently warned that climate change "will increase the risks of resource shortages, mass migration and civil conflict", while the MoD's view is that it will shift "the tipping point at which conflict occurs".

Image caption Armed forces are "the gas-guzzlers of the world"

Alejandro Litovsky, founder of the Earth Security Initiative, said that even without the increasing effect of conflict, prices of essential goods were bound to rise.

"From the year 2000 onwards, we have been seeing commodity prices climb, and this is not likely to stop," he said.

"It is primarily driven by resource scarcity, and the trends suggest that depletion of these natural resources is unlikely to be reversed in the near future without drastic interventions."

He also said that degradation of natural resources such as forests and freshwater was removing much of the resilience that societies formerly enjoyed.

Last week, multinational coffee house Starbucks warned that climate change threatened the world's coffee supplies in 20-30 years' time.

Compromised by carbon

The military officers at the meeting also emphasised the interest that armed forces have in reducing their own carbon footprint.

In Afghanistan, for example, fuel has to be delivered by road from Pakistan.

By the time it reaches its destination, it can cost 10 times the pump price. And the convoys are regularly targeted by opposing forces.

Several officers admitted that armed forces were "the gas-guzzlers of the world" - and while that was sometimes necessary in operations, reducing fossil fuel use and adopting renewables wherever possible made sense from economic and tactical points of view.

Rear Admiral Morisetti recalled that when commanding an aircraft carrier, it took a gallon of oil to move just 12 inches (30cm), while as many as 20 tonnes per hour were burned during a period of intensive take-off and landing.

"You can do that [with oil prices at] $30 a barrel, but not at $100 or $200," he said.

Health gains

On the health side, doctors warned of a raft of impacts, particularly in developing countries.

Hunger and malnutrition were likely to increase, and some infectious diseases were likely to spread, they said.

Poorer societies could expect to see an unholy symbiosis between the two, with under-nourished people more prone to succumb to infections.

Tackling carbon emissions, by contrast, would bring a range of health benefits, they argue in their statement.

"Changes in power generation improve air quality.

"Modest life style changes - such as increasing physical activity through walking and cycling - will cut rates of heart disease and stroke, obesity, diabetes, breast cancer, dementia and depressive illness.

"Climate change mitigation policies would thus significantly cut rates of preventable death and disability for hundreds of millions of people around the world."

No cause for optimism

As the UN summit in South Africa approaches, the statement here calls on the EU to increase its ambition and pledge to reduce emissions by 30% from 1990 levels by 2020, rather than the current target of 20%.

Currently, there does not appear to be political consensus for such a move within EU governments, however.

Additional recommendations are that developing country governments should analyse climate threats to their health and security, and that all governments should stop construction of new coal-fired power stations without carbon capture and storage (CCS) - which, as commercial CCS systems do not exist, would as things stand amount to a complete ban.

Without urgent action, carbon emissions could rise to levels that should cause major alarm, said Chris Rapley, professor of climate science at University College London.

Already, he noted, the atmospheric concentration of carbon dioxide has risen to about 380 parts per million [ppm] - whereas in the millions of years before the pre-industrial era, it fluctuated between about 180ppm during Ice Ages and about 280ppm in the warm interglacial periods.

"If we don't do something, then at the rate we're going, carbon emissions will continue to accelerate, and the atmospheric concentration is not going to be 450ppm or 650ppm by the end of the century, but 1,000ppm," he said.

"That is 10 times the difference between an Ice Age and an interglacial; and you have to be a pretty huge optimist to think that won't bring major changes."