On January 19, 2011, I got a phone call from two men who told me they were consultants for the CIA. Roger Lueken and Michael Canes, analysts for the Logistics Management Institute, asked, among other things, “If another country were trying to control our climate, would we be able to detect it?”

I told them that I thought we could, because if a cloud in the stratosphere were created (the most commonly proposed method of control) that was thick enough, large enough, and long-lasting enough to change the amount of energy reaching Earth, we could certainly see it with the same ground-based and satellite instruments we use to measure stratospheric clouds from volcanic eruptions. If, on the other hand, low clouds were being brightened over the ocean (another suggested means of cooling the climate), we could see telltale patterns in the tops of the clouds with satellite photos. And it would also be easy to observe aeroplanes or ships injecting gases or particles into the atmosphere.

At the same time, I wondered whether they also wanted to know if others would know about it, if the CIA was controlling the world’s climate. Given that the CIA is a major sponsor of the recently released US National Academy of Sciences (NAS) reports on geoengineering (which they have renamed “climate intervention”), the question arises as to the possible interest of the CIA in global climate control.

Let me be clear. I completely agree with all the NAS findings. Global warming is real and is being caused by humans, mainly by burning coal, oil, petrol and natural gas, which puts carbon dioxide – a greenhouse gas – into the atmosphere. Global warming will result in major harm to humanity if left unchecked. The solution is to stop using fossil fuels for our energy supply and switch to solar and wind power, and to adapt to some of the coming climate change.

Geoengineering by blocking sunlight should not be implemented now, as its risks and benefits are too uncertain, but we need more research on the various proposed scenarios. Taking carbon dioxide out of the air is a good thing, but currently extremely expensive, and we need research on that, too.

The 2014 US Quadrennial Defense Review makes clear that climate change poses a major threat to the US and the rest of the world. It says: “The pressures caused by climate change will influence resource competition while placing additional burdens on economies, societies, and governance institutions around the world. These effects are threat multipliers that will aggravate stressors abroad such as poverty, environmental degradation, political instability, and social tensions – conditions that can enable terrorist activity and other forms of violence.”

Certainly it is the job of the US military and the CIA to help protect our country from such threats, and it is not surprising that the CIA is interested to learn about geoengineering. In fact, the CIA opened a Center on Climate Change and National Security in 2009. When it was forced by Congress to close it in 2012, it said they would continue working on these issues anyway.

Whether you see the role of the CIA in climate change as nefarious or protective depends on how you weigh evidence with your preconceived notions. There is a long history of weather and climate control being proposed for military purposes, as described brilliantly in the 2010 book by James Fleming, Fixing the Sky, but there is no evidence the CIA is doing anything wrong on this issue. I know of no way to control local or regional climate with geoengineering without effects elsewhere, but while it is possible that such techniques could be developed by research, geoengineering for hostile purposes is prohibited by the United Nations Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques.

I don’t want to be working on geoengineering. But I don’t yet see the political will in the world to address global warming. If the US enhances its research efforts on geoengineering, we will learn about both the potential risks and benefits of its implementation, so that future policymakers will be able to make informed decisions, and not hasty ones in a panic if confronted by environmental dangers.

My recent work lists five potential benefits and 26 potential risks of stratospheric geoengineering, and the number one benefit – if stratospheric geoengineering is possible at all (an important research question) – is that it could cool the planet, reversing some of the dangers of global warming. But will we ever be able to overcome the governance and ethical issues?

Thus further research is urgently needed. In the meantime, we need to vigorously move to a carbon-free energy system.