Direct cooling of the planet

Walter Jehne spoke in Whangarei on 2 March at NorthTec’s Te Puna o te Matauranga marae. He was inspirational and all the feedback I have heard from his audience has been very positive. We will make video of his presentation available soon. If you are not familiar with Walter’s message, read about it here.

Walter Jehne

Photo credit: Nina Matenga

The climate solution is bigger than CO2

For me, Walter’s key message is the role of the hydrological cycle in cooling the planet. He tells us that CO2 drives 4% of the heat dynamics of the planet. So focusing on emissions reductions and sequestration is like taking a knife to a gun fight – and its a short knife that is pretty blunt. The hydrological cycle accounts for a massive 95% of the heat dynamics.

I am a fan of Project Drawdown because it expanded my thinking about the range of solutions available for mitigating global warming. The fact that food (31%) and land use (14%) accounted for 45% of the Drawdown solutions is especially significant for Northland. If we achieve the drawdown Paul Hawken advocates we could start to reduce CO2 levels by 2050. We could still do all of that stuff, but acting on Walter’s guidance we can achieve it so much sooner. This includes big global projects like reversing desertification that will require research, action and (the hardest task of all), collective will.

Implications for us

Walter told us that in his city, Canberra, the temperature in urban areas with lots of trees can be up to 12 degrees cooler than areas close by with little greenery. So if I can cool my little patch of earth down, surely that aggregates to cooling the whole planet?

What can we do in Tai Tokerau? This page from theNorthland Regional Council establishes Northland’s land area as 1.4 million hectares. Of that 52% is pasture. If we remove rivers estuaries and lakes from this equation, there are four types of cover that make up 95% of our land cover.

Land cover class Class hectares percentage
Pasture 735,400 53.2%
Indigenous forest 268,740 19.4%
Exotic forest 187,550 13.6%
Mixed indigenous shrubland 122,760 8.9%

Table 1: Adapted from Northland Regional Council 

Lets take a closer look at each of these and explore how they could contribute to cooling.


As stewards of 53% of our land cover, farmers have potential to be the stand-out heroes in our quest to cool the planet. So some of us have to stop hating on them and support the farmers who are leading the way with regenerative farming practices.

And by the way, Walter blew the methane argument out of the water. Actively growing pasture produces hydroxyl ions as water evaporates. Hydroxyl oxidises methane, and healthy pasture will produce about 100 times the amount of hydroxyl required for that oxidation. So Walter suggests that if you were to get a bill for methane emissions, send back a return invoice for your hydroxyl production.

Farmers can do many things to support cooling, focused on building the soil sponge (getting carbon into the ground) diversifying pasture and including more trees in the farm landscape.Our case studies of Northland farmers reveal how they are achieving this.  Please share examples of farmers who are doing this.

The other heroes are the ruminants who convert pasture into fertiliser, the pasture species that produce the sugars that feed the soil building microbiome.

Lindas stock

Photo credit: Linda Matson

We can help regenerative farmers by buying their product directly and encouraging policy change to make regenerative farming the gold standard. This includes agencies such as MPI who offer no tangible assistance to regenerative projects.

Indigenous forest and mixed indigenous shrubland

Our forests are struggling with exotic pests consuming tonnes of foliage daily, the incursion of exotic weed species and the early impacts of climate change. Extending them, and removing pest species will help to enhance their cooling potential. All of those people in land care groups are helping directly.

Also helping is the Northland Totara Working Group. They are promoting full canopy cover forestry by selectively logging totara on farms and managing totara stands for a sustainable harvest.


Parihaka in Whangarei

Exotic forests

Pines are vilified, but they are better than me at sequestering carbon. I am not sure what their cooling potential is, but that is for us to find out. They cover 13.6% of our land. How much more space should they have? Are there other species we can plant to diversify the productive landscape.

Homes, urban areas and roadsides

We can all contribute, perhaps simply by letting our lawns grow a little longer, returning the clippings directly to the land and planting more trees, vines and shrubs. Since Walter mentioned deep-rooted vines as especially good for cooling, I noticed a lot of stark and ugly wire mesh fences in Whangarei. Perhaps our councils can ramp up the provision of spaces for planting campaigns? And perhaps we could have more roadside planting? There are long straight stretches of road, where trees wouldn’t obstruct visibility and might shade the asphalt that gets so hot in the summer. If we ran out of straight road, would you be averse to reducing the speed limit to compensate for possible reductions in visibility – or would that be too inconvenient?

Some goals for a cooler Tai Tokerau

  1. Achieve policy support for transitioning all Tai Tokerau pasture to regenerative stewardship by the 2020 election.
  2. Achieve 100% regenerative pasture stewardship by 2030.
  3. Crowdsource public funds and labour to support appropriate tree planting on farms.
  4. Secure resources and public support for the eradication of forest pests.
  5. Extend coverage of indigenous forest from 268,740 hectares to 300,000 hectares by 2030.
  6. Establish roadside plantings for 200 km of road by 2030.
  7. Identify areas of public land that can be planted.
  8. Provide property owners with the knowledge required to cool their properties.

Any more suggestions?

Walter in whare

Walter talking the the whare hui. Photo credit Nina Matenga

Thanks again Walter. Who would have thought that it is Australian saving the world?

4 thoughts on “Direct cooling of the planet

  1. Walter’s talk was great. I really enjoyed it all and especially the parts about how much CO2 can be cycled through the soil, and how important total soil cover is for cooling everything down.
    It is a pity there was only one Govt representative (NRC) as this information is critical to how NZ will cope with the new climate – hotter and drier.

    Bill Mollison stated that 3 inches of good soil can hold 1 inch of rain, that is something that has stuck with me for many years now.

    I have created quite a few swales on our property to get water down into the soil so that as we plant trees there is a deep storage of water for the roots to get to without the problem of evaporation. The tree roots bring subsoil water to the topsoil, thereby supplying the all important soil biota.
    Even though our property is small, I hope that it can be one example of what can be done to help remediate the hydrological cycle, and therefore help mitigate the hotter, drier conditions we are now entering.

    The purpose of a swale is slow the downhill rush of rainfall and to spread it across the landscape so that it has time to infiltrate through the topsoil, and into the subsoils, in the same manner as forests do.

    One way to help with the hydrological cycle in farmland is increase the quantity and especially the variety of species of trees in pastures.

    There are mixed systems of pasture and forests that not only improve the soil, and so also the hydrological cycle, but also benefit the health of the stock that run through them.

    One method is to plant trees (with or without swales) along a contour so that there is a belt 5-6 trees deep with a narrow, or wide, pasture area (width depends on slope, soil condition, aspect, etc) extending downslope to another tree belt and so on. These tree belts infiltrate rainfall, provide shade and shelter, and – with the right species mix – also nutritional and medicinal effects.
    Healthier stock, healthier soil.

    One of ways Govt can assist with this providing fencing to farmers so that these tree belt plantings can get started.

    I also think the ‘billion tree’ program would be a lot more successful if a large amount of trees were provided free to farmers and anyone, rural or urban, who has space for trees.
    Some local councils in Aust used to provide free trees to farmers willing to plant them and urban home owners could also get 2 free trees per year.

    I also don’t think that increasing the amount pine plantations is at all a good idea as these are very short term cropped trees and are monocultures, both of which are very poor in soil biota. Selective felling, in widely diverse, permanent forest systems is definitely the way to go with forestry, ie the way it used to be done. The clear felling method works well for big machinery but not for soils or the ecology generally.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s