Heavy rains and widespread flooding killed nearly 200 people in western Japan; meanwhile, an unprecedented heat wave in eastern Canada killed around 70 people last week. Against this background, climate researchers are warning that casualties related to extreme weather events could increase if greenhouse gas emissions remain unchecked.

Extreme weather-related events are increasing worldwide, reminds Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research (PIK).

"Our Earth is once again being hit by extreme weather, including extreme heat and wildfires in California, and devastating floods of rain in Japan. Based on the laws of physics, due to global warming, we must expect more frequent and worsening events," he wrote in a statement.

Read more: 2017: The year climate change hit

Extreme weather events such as severe storms, unexpected and unpredictable floods, heat waves and unseasonable cold snaps have killed hundreds of thousands of people and injured billions more over the past 20 years, according to a joint 2015 World Meteorological Organization (WMO) and United Nations weather disaster report.

Scientists indicate that climate change is increasing the frequency and intensity of such extreme weather events, making it difficult for governments to prepare and respond to disasters. This is costing governments around the world billions, while taking an incalculable toll on human life.

‘Alarming numbers'

As disturbing as those numbers are, authors of 2017 study in The Lancet Planetary Health found that Europeans could die at a yet more alarming rate by the turn of the century.

According to the report, around 152,000 people in Europe could die per year directly from extreme weather hazards between 2071 and 2100 — that's 50 times more than what was recorded between 1981 and 2010.

Using state-of-the-art methods to analyze weather disasters in recent years, and forecasting those weather patterns on projected populations, the report found that heat waves would account for 99 percent of deaths during the projected period.

Giovanni Forzieri, a co-author of the study from the European Commission Joint Research Centre in Italy, says those projections could be worse.

"These estimates are really alarming, [but] our scenario is not the worst we could choose — it is the medium scenario of greenhouse gas emissions," he told The Guardian in 2017.

Europeans face more than a 90 percent increase in risk as a result of climate change, he noted, adding that the projected changes are brought about by global warming and the increasing amount of weather-related risks such as cold fronts and heat waves.

Read more: Extreme weather on the rise in Europe

Oversimplified estimates?

Even though the frequency of high-impact weather events has increased over past decades, Clare Nullis, media officer with WMO, told DW this hasn't necessarily correlated to an increase in the number of weather-related deaths.

Read more: Mother Nature's wrath: Is climate change making mega-hurricanes the new normal?

"Last year was one of the most expensive on record because of economic losses related to the hurricane season. But the death toll was certainly nowhere near the levels we saw a few decades ago," she says. "We need to be careful with the data because there are too many scenarios to consider," she continues. 

Ovais Sarmad, Deputy Executive Secretary of the United Nations Framework Convention on Climate Change in Bonn, Germany, told DW that the results of the study on weather-related risks to Europeans may also have been oversimplified, considering the many factors when gathering data.

"Although there are attempts to record this data, it has proven extremely difficult due to inaccuracies, underreporting and unreliable data," he says.

Sarmad also notes that around 50 percent of lives lost in extreme weather events are due to secondary impacts such as mudslides following torrential rains, adding to the complexity of reporting.

Nevertheless, Forzieri and his team anticipated scrutiny on the figures they released.

"Notwithstanding the fact that our estimates are subject to uncertainty, they do highlight important trends. Global warming, demographic changes and urban expansion could result in rapidly rising effects of weather-related hazards on human beings in Europe," the paper noted.

And the hazards are certainly not limited to Europe, researchers point out.

Paris Climate accord is key

Despite disagreement over exact figures, experts agree on how the world should react to offset increasing risk to human lives due to extreme weather.

"This trend can only be halted if the Paris Agreement for stabilizing our climate is rapidly and fully implemented," Rahmstorf states.

Read more: Winners and losers in the race to meet the Paris climate goals

Sarmad says the UN has worked on all levels with the 178 governments that have ratified the Paris accord, and that businesses and the private sector are also investing more time and effort into reducing greenhouse gases.

"The UN has engaged with non-party stakeholders and with governments to reduce greenhouse gases so that we can halt the worrying number of deaths related to weather disasters," Sarmad told DW. "This shows the importance in leaving a better environment for the next generation," he adds.

Such engagement includes better disaster preparedness, which Nullis points out as another key aspect in addressing the worrying trend.

"Climate change is certainly having a major impact on many aspects of our life, including food security, health, water management, and displacement. But better forecasts and better disaster risk reduction have helped to save lives."

Despite a sense of ennui around increasing ambition for climate protection goals under the Paris Agreement, many governments remain committed to limiting the impacts of climate change.

In an EU climate report released late 2017, two years after the adoption of the Paris Agreement, the EU said it  will reduce domestic emissions at least 40 percent by 2030.