As a result of Climate change, the world is experiencing more severe disasters, such as extreme heat waves, storms and droughts, and many governments are not sufficiently prepared to get early warnings out to their residents, according to a report from the United Nations released Thursday.

The report from the U.N. Office for Disaster Risk Reduction (UNDRR) and the World Meteorological Organization (WMO) found that half of countries do not have what it calls the “multi-hazard early warning systems” needed to ensure that their inhabitants have the earliest possible opportunity to prepare for disaster.

The U.N. is trying to emphasize the need for national governments to invest in such systems, and also the need for rich countries to subsidize those systems in developing countries, which are the most at risk from climate change and the least equipped to handle its damaging effects. In a video message released Thursday, U.N. Secretary-General António Guterres put the issue squarely on the table for November’s climate change conference in Sharm el-Sheikh, Egypt, known as COP27.

“Entire populations are being blindsided by cascading climate disasters, without any means of prior alert,” Guterres said. “People need adequate warning to prepare for Extreme Weather Events. That is why I am calling for universal early warning coverage in the next five years. The report reveals that such services are woefully lacking for those who need them most. At the COP27 climate conference in Egypt, I will launch an action plan to provide early warning systems for all within five years.”

But what exactly is a “multi-hazard early warning system”? Experts say it has four main components: understanding disaster risk, technical infrastructure to forecast the weather, a system for communicating that forecast to the public, and a government capacity for using that forecast to mitigate harm.

“Any warning system is better than nothing, but ideally it should be multihazard,” Omar Amach, a spokesperson for the UNDRR, told Yahoo News. What that means is monitoring for every possible cause and the cascading effect of a disaster.

“Most tsunami early warning systems watch out for seismic activity, earthquakes, and you will catch most earthquakes that way and let people know a tsunami might be coming. But if you look at recent history, there were a couple of examples of tsunamis triggered by events other than earthquakes,” Amach said. “So there was in Indonesia a tsunami that was triggered by a landslide, and then you have an example in Tonga of a volcanic eruption that then triggered a tsunami. So the idea of multihazard is that you shouldn’t just be watching for one hazard, you should be watching anything that could trigger the event.”

The same need to diversify what governments monitor for and warn about applies to effects as well as causes. “Another example in the context of climate change or climate disasters is: You look at any storm warning or, for example, Pakistan right now. It’s one thing to look at heavy rainfall and potential flooding, but then there are other risks that could cascade from that initial hazard,” Amach said. “So that could be landslides. Once you’ve had heavy rainfall, then there’s a risk of landslides. And so is the early warning system watching out for this type of hazard, and warning people that this now is an issue that they should be worried about?

“The early warning system shouldn’t just stop at one hazard and then people are off on their own, it should take into account different hazards that could result or cascade from the initial hazard,” Amach added.

In the United States, the National Weather Service has ample technology for tracking extreme weather events and can alert the public and elected officials through mass media, so utility companies can send out cellphone push notifications, for example. When Hurricane Ian approached Florida last month, the state government issued evacuation orders for 12 counties, and had it not done so, the death toll could have been much higher. Officials in Lee County were criticized for delaying evacuation orders longer than their neighbors.

But in much of the world, several of these components are missing, and the victims of natural disasters have little, if any, advance notice and chance to prepare.

“There are many countries, this report shows, that don’t even have the beginning parts of the chain,” Laura Paterson, WMO representative and coordinator to the United Nations, told Yahoo News. “You will struggle to find a good early warning ahead of flooding in many of the least developed countries in Africa. I’m thinking of South Sudan: Their [meteorological] service doesn’t have the capacity to really be ingesting all this data, making this decision on what’s going to be impactful and disseminating it out to their people. And also, perhaps many of the people aren’t receiving any warnings that they do have.”

When climate change-related floods hit South Sudan earlier this summer, not all of the 1 million residents affected received the warnings that were issued and thus missed the chance to move their goods to safer areas, such as higher ground.

One example of the kind of system Guterres would like to see in countries like South Sudan is a WMO program in Papua New Guinea. In 2015-2016, the Pacific Island nation endured severe droughts affecting about 40% of the population, causing life-threatening food shortages, and in response, the WMO launched a project there to build an early warning system to reduce the impact of drought. (Since warmer air causes more water to evaporate, droughts have become increasingly frequent and severe in many areas, due to climate change.)

The project includes increasing the national meteorological agency’s ability to predict droughts, and advance collaboration with government agencies such as Papua’s Ministry of Agriculture. Thanks to earlier warnings, Papuans in future droughts will have a chance to head off famine with such measures such as planting drought-resistant crops and stocking up on basic goods.

One key aspect of forecasting that needs to be improved worldwide is what the WMO calls “impact-based” forecasts. This specifies the potential impact, for instance, explaining not simply, “It will rain 6 inches in three hours,” but “It will rain 6 inches in three hours, which will flood the basements and ground floors of many homes.” Forecasts of extreme weather events are often expressed in technical terms — giving the temperature in degrees and wind speeds in kilometers per hour — that don’t make clear to the average person what is going to happen to them and what they should do to prepare.

This is an issue even in rich countries. After more than 230 residents of Germany and Belgium died in floods last year, local authorities called for better preparation for future extreme weather events.

“Even if we look at developed countries, and if you think of the example last year of the flooding of Germany and Belgium, that’s an example where the forecast was good. The predictions of how much rainfall was coming were good. In Germany, they have weather apps, they have good weather forecasts on TV; I’m sure people would have been aware that this was coming. However, the translation from ‘We’re going to get a lot of rain,’ to ‘Our community is going to flood so badly that it’s the worst we’ve ever seen and there’s going to be a risk to life’ — that step was quite challenging in Germany,” Paterson said.

Disaster warning systems are also only useful to those who have the means to take precautions such as evacuating. Even in the United States, local governments have failed to make accommodations to evacuate people with disabilities in the path of hurricanes, for example during Hurricane Katrina, which took 1,833 lives in 2005.

Recent catastrophes attributable to climate change have included the flooding of one-third of Pakistan’s land mass. Guterres, who recently visited the country to show solidarity, has called on wealthier nations to present more ambitious plans at COP27 for reducing their greenhouse gas emissions and for setting up a system to compensate developing nations for loss and damage from climate catastrophes.

“Communities everywhere are looking down the barrel of climate-driven destruction,” he said. “We must act — and we must act now.”