The impact of agriculture on global warming could be as high as 14 per cent says an agricultural greenhouse gas specialist.
But livestock may be even higher globally at 19 per cent.
Andy Reisinger​ the deputy director (International) of the New Zealand Agricultural Greenhouse Gas Research Centre said while the numbers were contentious, livestock made a substantial impact on climate change. 
Speaking by video-link from Mexico, where he was talking climate change with politicians, Reisinger addressed150 delegates at the New Zealand Agricultural Greenhouse Gas Mitigation Conference  in Palmerston North late last month.
Reisinger said it was hard to estimate different sectors' impact on global warming but the picture was clear.  
"From 1860 to 2017 there has been a massive increase in temperature, with 2016 so far the highest point.  As well as greenhouse gas production, there were also natural emissions,  which also takes into account the sun and volcanic eruptions.
"But the impact of agriculture today on greenhouse gases is surprisingly large.
"Livestock today, could be as much as 19 per cent of direct emissions."
He said gases from agriculture were not interchangeable.
"Carbon dioxide is the dominant greenhouse gas - it lasts in the atmosphere for thousands of years. Methane goes almost immediately.  
"But agriculture is one of the biggest contributors to global gases today. And we think it is responsible for about 14 per cent of global warming gases."
Resinger said of that, livestock was 9 percent at the moment.
"I just want to emphasise how much it is not known.  In 100 years, it looks as though agricultural will be 22 per cent of warming."
If no steps were taken to mitigate the world's temperature it would rise go up 4.5 degrees C. And if we do change and mitigate the effects, then the increase will be 1.5 degrees."
He said the message for all delegates of the conference was if the world took all mitigation steps, then livestock emissions would stand out.
"We came up with an aspirational goal to reduce agricultural emissions.  The proposal is for one gigatonne a year by the year 2030."
A gigatonne is equal to a million metric tons.
Reisinger said there was a groundswell of countries that thought agriculture needed to be included in any mitigation schemes.
"We have 119  countries included in the Paris agreement to reduce greenhouse gases.  And 64 per cent of those are developing nations.  They need strong support from developed nations."
He said agricultural mitigation was vital to support the Paris agreement.
"And the interest in mitigation of agriculture is growing internationally."
The director of the New Zealand  Agricultural Greenhouse Gas Research Centre, Dr Harry Clark, said while there were several mitigation factors for livestock in the pipeline, finding something that worked on grass-fed New Zealand stock was the most difficult.
Feeds that reduced emissions worked on animals housed and brought feed, they did not work on sheep on the hills.
However he said farmers' awareness of their greenhouse gas contribution was at a much higher level than 15 years ago.
"There is growing awareness now of the unusual greenhouse gas profile here dominated by agriculture.To meet our international commitments, we have to think carefully about what we do with the agricultural sector. I think 15 years ago, you wouldn't have seen that awareness."
But he said  other than more efficient production, greenhouse mitigation on New Zealand farms was years away.
He said many emissions in the US and Europe came from industry, such as power plants and from cars.
"You can get electric cars, and cleaner plants and a lot of those emissions will come down. Then unfortunately the focus will go on agriculture."
To get emissions down so global warming was 2 degrees Celsius or less, carbon dioxide emissions would have to hit zero this century, he said.
"Once you tackle those gases, then the proportion of gases change, and greater emphasis comes on agriculture."
Clark said New Zealand's immediate priority was to increase efficiency.
​"We need to do more research to develop new technologies. It is difficult to say when they will come along, but what we can say is very good progress has been made on the experimental side. However, then to go from experimental to something that works on farm and is available commercially, takes a number of years."
He said technology had to meet regulatory values and the nitrification inhibitor dicyandiamide, known as DCD and recalled from shelves in 2003, was a salutary lesson. 
"It has to be safe for people - have no residues, and be safe for animals."
The New Zealand Agricultural Greenhouse Gas Research Centre is funded by the Government and overseas investment. 
Statistics New Zealand says New Zealand's net greenhouse gas emissions increased 54 per cent between 1990 and 2014.
A total of 24.4 million tonnes of carbon dioxide (CO2) equivalent was removed from the atmosphere in 2014, equivalent to 30 per cent of New Zealand's total greenhouse gas emissions that year.

This article originally appeared at http://www.stuff.co.nz/business/farming/91005604/dr-andy-reisinger-livestock-impact-on-climate-change-set-to-rise
View Andy's presentation at http://www.nzagrc.org.nz/agricultural-emissions-their-role-in-climate-change-past-present-and-future.html