Earth Day was born on April 22nd, 1970, when 20 million people across the United States took to the streets to demonstrate support for environmental protection. Today, it has transformed into a global movement, one that is observed by billions of people around the world who annually pledge to undertake a 'green' initiative set by the Earth Day Network (a consortium of 22,000 partners across 192 countries), to help our planet.

With more than half of the world's population residing in urban areas and more inching their way in every day, it is only fitting that this and next year's focus is to create 'Green Cities' - help towns and cities become more sustainable by investing in renewable energy and reducing their carbon footprint. To do that, the campaign is focusing on every city's three biggest pollutants - Energy, Buildings and Transportation.

Energy

Given that most of our electricity is derived from fossil fuel power plants that release greenhouse gases into the air, energy is amongst the largest contributors of climate change. While powering entire entire cities using renewable energy may sound a little ludicrous, it is possible, if residents and city officials put their minds to it.

That is what happened in Reykjavik, Iceland, AKA the World's Greenest City, which derives over 80% of its energy from renewable sources like geothermal and hydrogen power. What makes their transition away from dirty fossil fuels even more interesting is how it all began. In 1907, a farmer began channeling the steam released from a hot spring below his land into a pipe, and used it to heat his house. Other farmers followed suit and by 1930, work began to power the entire city with the natural heat source. By weaning off its dependence on fossil fuels, the city has not only become more sustainable, but also, saved $8 billion USD - and that, is just in the last three decades.

Buildings

The gorgeous skyscrapers that are sprouting up in urban areas throughout the world have a dirty little secret - They are responsible for one-third of greenhouse gas emissions! The problem is even worse in the U.S. where commercial and residential buildings are responsible for emitting 40% of all carbon dioxide emissions. The good news is that the numbers can be reduced fairly easily since the emissions are caused by fossil fuels and inefficient energy use.

This can be changed by installing solar panels, adding better insulation and even something as basic as changing the color of the building's roof. That is exactly what the city of Los Angeles has in mind for new buildings starting 2014. The mandate which was announced in late December 2013, requires all new buildings to feature white roofs.

Why? Because according to Jonathan Parfrey, Executive Director of Climate Resolve, it helps keep temperatures down in the hot summers. This means that less power will be used, saving millions of dollars and, helping combat climate change at a local level. If that is not enough to convince naysayers, a cooler roof can also help save lives according to Arthur Rosenfeld, a physicist and energy researcher at the Lawrence Berkeley National Lab. In a recent report about the impact of roof colors, the scientist noted that when the city of Chicago was hit by an extreme heat wave in 1985, those that lived on the top floor of buildings with black roofs had been in mortal danger! Who would have guessed?

Transportation

Given the increase in urbanization, the fact that transportation accounts for 24% of greenhouse emissions and is the fastest growing source, should come as no surprise. But this trend can be reversed in no time, by building convenient and accessible public transportation systems, creating affordable fuel efficient and low-emission vehicles and of course, making cities bike and walk friendly.

One of the leaders in the last initiative is the city of Copenhagen in Denmark, where 36% of the residents bike to work or school, every day. This simple action saves the city 90,000 tons of CO2 emissions every year. While that is certainly impressive, the officials of the 'Biking Capital of the World', whose residents pedal 789,000 miles each day, are not satisfied. They want to encourage even more locals to join in and are doing everything they can, from adding more bike lanes to widening existing roads and even building bike bridges.

The best part about these 'green' initiatives is that if everyone does their share, the cities of the future will be pretty cool places to live in. Imagine 'living' buildings, self-driving electric cars, homes with their own turbines and sparkling solar panels, long distance travel inside hyperloop pods like those envisioned by Elon Musk and best of all . . . clean fresh air!

We can already smell it - Can you? Then be sure to do your part - Remember, even minor things like switching off unnecessary lights, planting a single tree, recycling a can, will help in the effort to reverse climate change!

Happy Earth Day!