I had a birthday on Saturday, but there was no time to celebrate. Instead, I was busy monitoring intensive discussions on climate change in Yokohama, Japan, where climate scientists from around the world were finalising their latest assessment report together with government officials whose role it is to make sure they understand what they're told about the impacts of climate change.

My job is to help spread the word. So while my friends were sending me birthday wishes and hearts on Facebook, I shared a link to our opinion piece on how climate change might fuel conflicts after it was published on Al Jazeera. Sorry guys, but there's just never a convenient time for this story.

That's a key issue reporters, observers and scientists have been trying to answer this week in the corridors of the IPCC meeting. How do you to tell a story that many people don't want to hear even though it's the defining story of our time? The inconvenient truth, as Al Gore once put it.

Burning oil, coal and gas for energy is turning our planet into a hostile place to live, threatening its beauty and the ecosystems we depend on. Our fingerprints can be detected everywhere: species are reacting to a changing environment, glaciers are melting at a stunning pace and worsening weather extremes around the world are revealing our glaring vulnerability.

The real problem is that this is just the beginning. It's going to get a lot worse, as the IPCC has just warned, if we continue to ignore reality.

So why don't we listen? And why do some people refuse to accept the facts, when the scientific consensus on climate change couldn’t be stronger?

I can associate with those feelings. I understand that climate change is so mind-boggling, that it sounds like it can't be true.

The thought that we could cause the world temperature to change as much in one generation than it did since the last ice age is difficult to fathom. That we might wipe out massive amount of species and dry up our forest areas is frightening. The possibility that we could set in motion irreversible melting of massive ice sheets is almost too enormous to contemplate.

This is the reality we face and although the scale of the challenge somehow doesn't make sense, not accepting the facts doesn't make them go away.

For many people around the world, climate change is no longer a theory. It has destroyed homes, lives and dreams. Some have tragically had their loved ones washed away by storm surges, like my colleague Amalie.

Civil Society Groups Call for Climate Action. 03/30/2014 © Jeremie Souteyrat / Greenpeace

People living with climate reality are not interested in academic debates on whether a single extreme weather event can be attributed to human-made climate change. It's the clear long-term trend that matters.

People often like things to stay the same. I do too. I don't want my grandparents' humble summerhouse next to a beautiful lake to ever change.

But if we want to maintain the wonders of our planet, including those I enjoy at the summerhouse, we have to change. Otherwise global warming will usher in a drastic global change and it won't be pretty.

So where's the hope? Positive change is already taking place, accelerated by people who are fed up with the old polluting energy system. Since the last IPCC report in 2007, renewable energy has made a breakthrough. It's bigger, it's cheaper and most importantly, it's ready to challenge the old system.

The hazards of coal, oil and nuclear are also more apparent, from the Deepwater Horizon oil spill to Fukushima and the apocalyptic air pollution problem caused by coal burning in China. This has sparked an accelerated transition to clean and safe energy.

That's where the hope lies: Climate solutions are attractive on their own, even for those who don't want to hear the climate message. To be part of the change, you don't need to wait for leaders to act. You can be the leader.

So let's understand the urgency, but not be paralysed by it. There's a better future out there than the one we're facing and it's ours if we want to grasp it.

Read more:

Greenpeace briefing on IPCC key findings

Greenpeace blueprint for clean energy future: http://greenpeace.org/energyrevolution

Kaisa Kosonen is a Senior political advisor for Greenpeace International.