As Canada's Environment Minister pushes forward plans to dramatically cut carbon emissions, she is lashing out at "gender climate deniers" who fail to acknowledge that in a warming world, women fare worse.

Such people are a "grouchy subcategory" of climate deniers, Catherine McKenna said after hearing from outraged critics on social media who mocked the notion that "climate change is sexist."

Ms. McKenna advocated for greater recognition of the gender dimension to climate in Tokyo this weekend at a G7 environment ministers meeting, where leaders agreed to push for early entry into force of the Paris climate agreement – although she suggested that may not happen by year's end. She was joined in Japan by Vancouver Mayor Gregor Robertson to discuss the role of cities in climate change; Vancouver wants more federal transit funding.

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But Ms. McKenna sparked debate at home when she brought the argument on women and global warming to Twitter.

Did you know, the former lawyer wrote, that climate change "is not gender neutral? Women are more vulnerable to the effects of climate change than men."

The response was swift, and angry.

"Is it April 1st already? Our 'leaders' actually think like this?" one person wrote back on Twitter. Another asked: "Do Liberal MPs have a bet to see who can sound the stupidest? Cause you just took the lead."

In an interview Monday, Ms. McKenna said she was "surprised by the vehemence of some people's comments," but said it's time the world "recognize that as we develop polices, we look at how do we support women, how do we support women's rights. That's a theme of our government – it's been set by the top by the Prime Minister. And I think it's a key piece in the climate discussions which is sometimes lost."

Ms. McKenna pointed to a United Nations fact sheet that lists how women's "unequal access to resources and to decision-making processes" leaves them less mobile and therefore more vulnerable. The large numbers of female farmers in developing countries, meanwhile, are uniquely susceptible to climate changes that make "traditional food sources become more unpredictable and scarce. Women face loss of income as well as harvests – often their sole sources of food and income," the UN says.

Though formally charged with Environment and Climate Change Canada, Ms. McKenna has emerged as a prominent voice on women and family issues, pledging to turn off her BlackBerry every night between 5:30 and 8 p.m., a stance that has won her praise from people like philanthropist Melinda Gates.

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On the gender dimension to climate change, Ms. McKenna echoed Prime Minister Justin Trudeau's blunt statement that he selected a gender-balanced cabinet "because it's 2015."

"It's just true," Ms. McKenna said.

But elements of the argument do not hold up well to scrutiny, including the notion that women are poorer than men, and therefore more vulnerable.

In 1995, a UN Development Programme report produced a much-cited statistic that said "women still constitute 70 per cent of the world's poor and two thirds of the world's illiterates."

Conservative MP Michelle Rempel cribbed from that statistic when she took to Twitter Sunday to support Ms. McKenna. "Food security has disproportionate impact on those in poverty, and women disproportionally experience poverty," Ms. Rempel wrote. Ms. McKenna, too, said on Twitter that "the majority of the world's poor are women, and their income is dependent on natural resources that are threatened by climate change."

But there is scant factual basis for parts of that statement.

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In 2008, a scholar at the London School of Economics surveyed South American countries and found that while women are poorer in rural areas, "differences are for the most part, fairly marginal." In the urban areas of 10 out of 17 countries, meanwhile, poverty was either equally distributed, or worse for men.

In 2013, a World Bank "state of the poor" report plainly stated that, worldwide, "the poor are equally divided by gender."

The UN itself has disavowed its previous number: "I conclude that the citation of 70 per cent of the world's poor are women is inexplicable except as a mistake," Robert Johnston, former chief of statistical services at the UN Statistical Division, told Politifact in 2014.

Are women nonetheless more vulnerable to natural disasters, of the sort expected to appear more frequently with climate change?

A 2007 study said the answer is yes: "Natural disasters lower the life expectancy of women more than that of men," concluded researchers at the London School of Economics and the University of Essex.

"Natural disasters do not affect people equally as if by an arbitrary stroke of nature," they wrote. "Instead, the disaster impact is contingent on the vulnerability of affected people."

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But this study is founded in part on the same idea that women are, on average, more impoverished: "There is general agreement that poor people on average are more likely to be female," the authors write.

Still, international organizations have tallied that women made up 61 per cent of the deaths from Cyclone Nargis in Myanmar, some 70 to 80 per cent of the dead from the Boxing Day tsunami in the Indian Ocean and 91 per cent of deaths from the 1991 Bangladesh cyclone.

The differences owe to many reasons. Cultural dress expectations can obligate women to wear clothes that hamper running. In some countries, boys are taught to swim, but not girls. Women who stay at home are more vulnerable to earthquakes and tsunamis than men who sleep outside or work out at sea. Women aren't always alerted to imminent disaster, and men can hog relief supplies.

But some differences are more complicated than mere sexism. Pregnant women, for example, are at a disadvantage in fleeing disaster.

And in some calamities, women fare better. Droughts, for example, tend to kill a disproportionate number of men, since woman, according to the natural disaster study, "can better cope with food shortages due to their lower nutritional requirements and higher body fat."