>> A landmark global pact to combat climate change entering into force Friday. The 2015 Paris agreement has been signed by almost 200 countries worldwide. It commits nations to slash greenhouse gas emissions and limit global warming. The treaty gained the support it needed in early October, with 55 nations agreeing to it and allowing it to come into force 30 days later.
However, around 100 countries have yet to ratify it. And the United Nations say that many of the countries' current pledges
e insufficient. The agreement seeks to limit the rise in average world temperatures to below 2.0 degrees Celsius in the second half of the 21st century. But the UN says the world could still be on track for a temperature rise of 3.4 degrees by 2099.
The next round of climate talks starts Monday in Marrakesh. Environmentalists say those involved in the treaty must keep pushing for action if the Paris agreement is to reach its goals.>>