I very much welcome this petition and the opportunity to speak on it. When historians look back on the National Assembly for Wales, they'll be astonished at how much time has been spent on how we trade with other countries and how little time we have given to the threat to our world and all species, including ourselves. It's beyond serious argument now that we're seeing climate change, and that unless action is taken now, we will see it getting worse and worse.

I'm pleased the Welsh Government has announced a climate change emergency. This declaration sends a clear signal that the Welsh Government understands that climate change threatens our health, economy, infrastructure, natural environment and, basically, ourselves. Tackling climate change is not an issue that can be left to individuals or to the free market. It requires collective action and for the government to have a central role in making that collective action possible.

I support the Welsh Government in its commitment to achieve a carbon-neutral public sector by 2030 and to co-ordinate action to help other areas of the economy to make a decisive shift away from fossil fuels, involving academia, industry and the third sector. If you look at the science, firstly, carbon oxidises into carbon dioxide. Carbon dioxide is a greenhouse gas. How do we know that? Compare Venus with Mercury. Mercury is about 58 million km from the sun, Venus is approximately twice as far at 108 million km. So you'd expect Mercury to have a hotter surface than Venus. The opposite is true. Why? It can only be about the atmosphere. Mercury's atmosphere contains small amounts of hydrogen, helium and oxygen. The atmosphere of Venus is layers of gases surrounding Venus. It is composed primarily of carbon dioxide. That means that it holds the temperature. We know that. It's not a matter of argument or, 'I don't believe in climate change', or 'I don't believe in carbon dioxide and greenhouse gas'—the facts are there. This is conclusive proof that carbon dioxide traps heat and makes the surface hotter.

'But we have carbon dioxide in our atmosphere now', people say. Yes, if we didn't have carbon dioxide, we would not have the temperate climate that exists on most of the earth. It traps heat. What we know is that if we get more carbon dioxide, the planet will get hotter and hotter.

As climate change takes place, our daily weather and normal temperatures will change, and the homes of plants and animals will be affected all over the world. Polar bears and seals are a good example of animals that will be affected by climate change. They'll have to find new land for hunting and living if the ice in the Arctic melts, but the fact is—more realistically—that these species will almost certainly become extinct.

Anyone over 50 will have noticed how our weather has changed in Wales. Simple things such as the end of persistent drizzle—which we used to have for days and days on end—have now been replaced by short periods of very, very heavy rain, which has led to flooding in many areas.

Looking at the rest of the world, starting with the United States of America—which is the best place to start, because it's the home many of the deniers—heat waves and droughts in Texas and the midwest set records for highest monthly average temperatures. Multimonth extreme heat has been unprecedented since the start of reliable instrumental records in 1895. Higher temperatures lead to increased rates of evaporation. Recently Texas and Oklahoma experienced more than 100 days over 100 degrees Fahrenheit. Both states set new records for the hottest summer since record keeping began in 1895. Heavy downpours are increasing nationally, especially over the last three to five decades. The heaviest rainfall events have become heavier and more frequent, and the amount of rain falling on the heaviest rain days has also increased. Since 1991, the amount of rain falling in very heavy precipitation events has been significantly above average. America is suffering; the rest of the world is going to follow.

Turning to Africa. New research says the continent will experience many extreme outbreaks of intense rainfall over the next 80 years leading to floods, storms and farming failure, moving from intense rain every 30 to 40 years to intense rain every three or four years. This will be interspersed with crippling droughts that will also affect food production.

A four degree warmer world will lead to drowned cities, drowned island nations, stagnant seas, intolerable heatwaves, huge areas uninhabitable and over 11 billion people trying to live on it. A four degree warmer world is the stuff of horror movies—a sort of apocalypse coming to you shortly. This is, unfortunately, the direction we are heading in if we fail to reduce carbon dioxide increasing in the atmosphere to stop global warming. Nice words and limited action are not an option. We only have one world. For the last 200 years we have abused it. Unless we take action now, then we are in danger of destroying it and most life forms, and that includes our own.