Luckily, chemists are inventing a new way of making cement that cuts down on the release of that CO2. L.C 3 uses Calcine clay: it is heated to around 800 degrees Celsius, (significantly lower than the 4050 needed to produce cement.) and there are no CO2 emissions from the decomposition of limestone. It can be produced with the same equipment and processes and used in the same way, but has up to 40 percent lower CO2 emissions. It acts as a direct replacement with all the same properties and yet saves more than a third of the CO2 pollution.

Karen Schreiber - Chemist 

To make this work, we need this kind of pincer movement. <ol><li>bottom-up pressure = people making these changes on their own (bike more /transitioning from an internal combustion engine car to an electric car) </li><li>topmost level/national level = mandates that lock in some of this progress, (certain number of electric vehicles for the government's own vehicle fleet/emission standards for all the vehicles that are out there)</li></ol>

Monica Orea - transportation expert 

Despite already promoting biking, public transit, walking, there is a problem with air pollution because of road transportation. But Amsterdam has a plan to go emissions free by 2030.

Cooling systems today collectively account for 17 percent of the electricity we use worldwide – because of climate change, we need even more energy to cool ourselves, our homes, our data centres, everything. We are trapped in this vicious cycle of where global warming makes the world hotter. That drives demand for cooling, which then drives emissions, which then make the world hotter and so on and so forth.

Yvonne Acky Sawyer is the mayor of Freetown, which is in Sierra Leone. Freetown has been suffering some of the extreme weather due to climate change. She ran for mayor with the goal to increase vegetation cover by 50 percent in Freetown by the end of her term in 2020.This is not just to help fight to help fight climate change -- these trees are about improving the lives of residents of Freetown.  But trees don't in the time frame we need solve the problem of climate change.

Yvonne Acky Sawyer - Mayor

Tom uses the idea that they could cure the concrete with pure CO2 itself, trapping it inside. This could transform the third largest emitter as a country in the world to a net sink.

Tom Schuler -mechanical engineer/professor/CEO of a cement startup 

Luckily the technologies we need for this transformation are here today commercially available, getting cheaper and getting better.E.G the huge bus fleets in China are being switched over to electric : single biggest thing that has been done in the transportation sector for climate change emissions.

Californians use more electricity playing video games than the entire country of Senegal uses overall – this is an example of the global energy inequality.

This is where the concept of sky cooling comes in. It was inspired by ancient Persians: They would spread water out in the desert, in the hot desert, in a thin layer, and overnight it would form ice. And then that ice could be stored in cooling warehouses.

Aswath Román - electrical engineer 

That ice formed, even though the temperature never dropped to freezing.This is because of a window in our atmosphere: Certain wavelengths of heat pass right through our atmosphere and back out into space. So even though the outside air is not below freezing, heat from the water escapes into space and the water cools and it freezes

Africa must be prioritized when it comes to what's left in the carbon budget.For three main reasons:<ol><li>First Africa isn't the culprit of climate change. It's a victim, facing the worst impacts of extreme weather, drought and heat. Yet forty-eight African countries combined are responsible for less than one percent of a cumulative carbon dioxide in the atmosphere.</li><li>Second, Africa needs more energy to fight climate change because of its climate vulnerability. Africa's climate fight is about adaptation and resilience, and climate adaptation is energy intensive. To respond to extreme weather, Africans will need more resilient infrastructure (to cope with drought/pumped irrigation for agriculture/ desalination for fresh wate/cold storage and AC)</li><li>Third, preventing African development in the name of the climate creates a two-tier global energy system with "energy abundance for the rich and tiny solar lamps for Africans."</li></ol>

Rose Muto - clean energy researcher 

Sadly, the world is looking at Africa in a completely contradictory way.<ul><li>When one side wants them to grow, to emerge from abject poverty, to build a middle class and become the next global market</li><li>But, anxious to demonstrate action on climate change, rich countries in the West are increasingly restricting their funding to only renewable energy sources, effectively telling Africa and other poor nations to either develop with no carbon or to limit their development ambitions altogether.</li></ul>

<ul><li>Billions of people in LEDCs simply lack enough energy to build a better life. (ie to run their businesses without daily blackouts/preserve their crops from rotting/power lifesaving medical equipment) Unreliable, expensive energy prevents them from growing and prospering with dignity and opportunity</li></ul>

But electric cars aren’t fool proof, sometimes what has happened is that tailpipe has moved many miles away.We hope that the electric comes from to a solar farm but in most cases it comes from a coal fired power plant. In order for electric car to be sustainable, we must have green power.

There's twice more carbon in soil than there is in vegetation and air - hence a very small change in the amount of carbon stored in soil can make a big difference in maintenance of the Earth's atmosphere. The main problem is most of our agriculture is designed in a way to extract that carbon. (via deforestation, itensive crop harvesting etc) Luckily, one of the best ways to get soil working to stop climate change is to plant trees, reforestation

Morat Asawa Burke – Soil researcher 

Yet US and China have been burning through the carbon budget with no restrictions, allowing them to develop to where we are today. Africa has not benefited from that. And so, any remaining carbon budget should be allocated to them so that they can enjoy kind of similar lifestyles to those enjoyed by those of us in the United States and China.

Concrete is made with limestone (fossil carbon), which requires the burning of fossil fuels to get to super high temperatures that allow you to break down the limestone and turn it into concrete.Yet concrete is an intrinsically low impact material with much lower emissions of CO2 and energy per ton than other materials like iron/steel/bricks. It is the second most used substance on earth and so contributes to about eight percent of manmade CO2 emissions.

Aswath created a multilayer optical material, more than 40 times thinner than a typical human hair, and able to do two things simultaneously. <ol><li>First, it sends it heat out precisely where our atmosphere lets that heat out the best, targetting in the window to space.</li><li> Second thing it does is it avoids getting heated up by the sun. It's a very good mirror to sunlight</li></ol>

Fighting climate change is a big, messy task that will take a lot of work. This hour, TED's Science Curator David Biello joins Manoush to share some promising and fascinating solutions. 

DAVID BIELLO