Our planet is changing. So is our journalism. This weekly newsletter is part of a CBC News initiative entitled "Our Changing Planet" to show and explain the effects of climate change. Keep up with the latest news on our Climate and Environment page. Sign up here to get this newsletter in your inbox every Thursday. This week: Emerging tree diseases are on the rise, threatening the planet's largest plants Big Oil's newest climate defence Steamy September caps record-shattering summer — and scientists warn trend shows no sign of stopping Emerging tree diseases are on the rise, threatening the planet's largest…