[2] He recalls that "by the time I'd followed this theme through a post-doc at the University of Illinois in the States, I was ready for a change and came back to New Zealand to work for the Meteorological Service at Kelburn in Wellington.

"[1] The aim was to work collaboratively with Crown Research Institutes (CRIs) and universities to develop of "tools and science-based policies for reducing greenhouse gas emissions and adapting to climate change.

Wratt, along with Dave Lowe and Brett Mullin responded to de Freitas with data that showed the rise in worldwide temperatures was real and this could be largely attributed to human activity.

[14] When de Freitas, Dedekind and Brill in 2015 published a paper that questioned the reliability of previous analyses of regional long-term data used to detect trends in global climate change, focussing particularly on New Zealand,[15] Wratt, along with other scientists Mullan, Jim Salinger and James Renwick published Comment on A Reanalysis of Long-Term Surface Air Temperature Trends in New Zealand (2018).

[16] In this paper they identified what they considered were "methodological flaws" in the document by de Freitas (et al.) and listed several lines of evidence pointing to an increase of 0.7 to 1.0 °C per century for New Zealand temperatures.

Wratt and his colleagues argued that the increase of temperatures of New Zealand land surfaces for the period 1909-2009 claimed by de Freitas et al. were too low.

[19] In the New Zealand Herald, Wratt said that the judgement was clear and that "while it is important for scientists to have an open mind, the research and data from around the world showed the big picture, which is that the climate has warmed and this is very likely due to increases in greenhouse gases."

[21] The findings of this programme, that explored how the Alps influence New Zealand's weather and the climate were later published in a journal article co-authored by Wratt.

[22] The study used rain gauge and radar observations to show how precipation varied across the Alps during a northwesterly storm in 1994 and concluded that this information was critical to accurate forecasting of floods.

These climate predictions provided estimations about the vulnerability of environmental, economic and social systems and their ability to respond and adapt for periods of 50 years from 1970 to 2099.

"[27] The introduction to the paper stated that climate change in the future depended on the degree of greenhouse gas and aerosol concentrations in the atmosphere and how these were responded to - specifically identifying and managing socio-economic developments that contributed to these levels.

The report recommended a strengthening of the role of TGICA and upgrading the Data Distribution Centre (DDC) by establishing an improved dataset index that would gather information effectively through accurate recording of primary sources, appropriate citations and keywords.

The chapter noted the importance of local government in facilitating adaptation to climate change at local and regional levels and suggested New Zealand had a model that enabled this process, specifically by raising community awareness, utilising the expertise of professionals, systematically assessing risks and identifying vulnerabilities in an area, and getting support from central government.

[30] Co-authored by Wratt, this paper examined the economic implications of climate change to agricultural production in New Zealand and summarised the knowledge at the time to predict the likely costs and benefits of adaption.

The article recommended farmers should consider some of the predictions about temperature increases impacting the drying and growth of pastures and make changes as necessary to maintain production.

[33] Wratt was a Lead Author for this document which presented an overview of scientific information on the complexities of climate change based on the peer-reviewed literature available in mid-2006.

[35] This article looked at the different ways that the impact of temperate climatic factors were estimated and mapped in New Zealand to inform land-use decisions about the best crops to grow in an area.

It was further stated that knowledge of the technique used in mapping, could "reduce the risk that farmers will try to grow a new crop in an area where the climate or soil is unsuitable.

[44][45][46] Writing in the New Zealand newspaper Stuff, Andrea O'Neil noted:"You won't find a more modest award recipient than Tawa climate change scientist Dr David Wratt.