Schierl, Inc., Wisconsin Central, Ltd., and Sault Ste. Marie Railway Co. appeal from a summary judgment dismissing their cross-claims against David Seidl. Plaintiffs Ronald and Jeanna Kin-nick and others brought the underlying action, alleging that the appellants are responsible for contaminants in the water wells on the plaintiffs' properties. Appellants cross-claimed against Seidl for contribution, alleging that he is also responsible for the contaminants. We affirm the judgment.
The questions are: (1) whether factual issues exist which must be tried, (2) whether the undisputed evidence is such that expert testimony is necessary to establish a causal link between the contaminants in the plaintiffs' wells and the contamination found on Seidl's property, (3) whether the trial court prematurely granted summary judgment to Seidl, and (4) whether, in any event, the court erred by dismissing the cross claims with prejudice. We conclude that because of appellants' inability to establish by expert testimony that contamination from Seidl's property contributed to the contamination in the plaintiffs' wells, the court properly granted summary judgment *861dismissing the cross claims and did not act prematurely. We affirm the judgment, without deciding whether the court erred when dismissing the cross claims with prejudice.
It is undisputed that the plaintiffs' properties are contaminated with the same kind of contaminants found on the properties of the appellants and Seidl's property, and that the contamination occurred via underground routes. If contaminants migrated from Seidl's property and from the appellants' properties to the plaintiffs' properties, then appellants may be entitled to contribution from Seidl.
Seidl moved for summary judgment on grounds that whether contaminants migrated from his property to the plaintiffs' is a factual issue requiring special knowledge, skill and experience outside the realm of the ordinary experience of mankind, especially where there are various potential sources of the contamination. He asserted that the testimony of an expert witness, qualified to render an opinion regarding his property as the source of the contaminants in the plaintiffs' wells, is necessary for the appellants to have contribution from him.
The trial court granted summary judgment to Seidl dismissing the appellants' cross claims after finding that no party to the litigation has an expert witness who will testify to a reasonable degree of probability, or even to a likelihood, that contaminants migrated from Seidl's property to the plaintiffs' properties.
Appellants assert that undisputed expert testimony showed that "possible" routes exist for the contaminants to have migrated from Seidl's property to the plaintiffs' properties. They rely on the undisputed facts that plaintiffs' properties are contaminated with the same kinds of contaminants found on Seidl's prop*862erty and the appellants' properties. They argue that, drawing every inference in favor of the appellant co-defendants, a genuine dispute as to material facts exist and therefore summary judgment should not have been granted. We disagree.
We consider the necessity for expert testimony without deference to the trial court's opinion. See Cramer v. Theda Clark Memorial Hospital, 45 Wis. 2d 147, 150-53, 172 N.W.2d 427, 428-30 (1969). However, appellants concede in their joint brief that the migration of contaminated groundwater is an extremely complicated, technical matter, and ascertainment of it requires considerable expertise, along with extensive and expensive site investigation. This concession is enough to establish that expert testimony is required to prove that contaminants migrated from Seidl's property to the appellants' properties.
At trial the burden of proving that the described migration has occurred, for purposes of obtaining contribution, will be on the appellants. When expert testimony is required and is lacking, the evidence is insufficient to support a claim. Cramer, 45 Wis. 2d at 152, 172 N.W.2d at 429. Because appellants lack the necessary expert testimony, we conclude that no factual issues remain to be tried, and Seidl is entitled to summary judgment dismissing their cross claims.
Appellants nevertheless assert that because experts believe that the Seidl property is a "possible" source of the contamination to the plaintiffs' properties, and because when Seidl's motion was made they were seeking additional investigation to ascertain the contamination routes, the trial court prematurely granted summary judgment to Seidl. We disagree. *863”[A]n expert opinion expressed in terms of possibility" is insufficient and is inadmissible in evidence. McGarrity v. Welch Plumbing Co., 104 Wis. 2d 414, 430, 312 N.W.2d 37, 45 (1981).
Appellants assert that the court's ruling denied them fair opportunity to develop their case, because when Seidl's motion was heard, the trial date was seven months away, discovery cutoff was six months away, and they had asked the trial court to enter a "Lone Pine order." The term "Lone Pine order" originated in Lore v. Lone Pine Corp., a New Jersey toxic tort case against a landfill operator and the generators and haulers of toxic materials to the landfill.1 In a case management order, the Lone Pine trial court directed the plaintiffs to provide, within four months, expert opinions supporting their personal injury and property damage claims, including opinions regarding *864causation by substances from the landfill. Id. at 137-38. When the plaintiffs did not comply with the order, the court dismissed their cases with prejudice.
A Lone Pine order is not a condition precedent to summary judgment dismissing a toxic tort case. Whether to impose the order is within the trial court's discretion. The trial court said that after considering such an order, it could not enter it and be fair to Seidl and other parties who moved for summary judgment.
The record supports the trial court's ruling. As the order granting summary judgment recites, this action was commenced on November 6, 1991. The court had set numerous scheduling conferences and scheduling orders since then. The plaintiffs named their expert witnesses in 1992 and the appellants named their expert witnesses on March 1, 1993. By May 3, 1993, when the trial court heard and granted Seidl's motion for summary judgment, all parties acknowledged that no party had an expert witness who would testify to a reasonable degree of probability that contaminants from Seidl's property reached the properties of the plaintiffs.
We understand the trial court to have reasoned that after so much time and effort had elapsed, whether the appellants could obtain expert opinion favorable to them was "pure speculation," and the court was "afraid [what] a Lone Pine order is going to do to the entire schedule." When asked to reconsider its order to dismiss the cross claims with prejudice, the court expressed concern that Seidl (and others who had *865moved for summary judgment) "are expending a great deal of money over a great period of time."2
We conclude the trial court did not erroneously exercise its discretion when it declined to enter a Lone Pine order granting the defendants additional time.
Co-defendants assert that § 802.08(4), Stats., mandates a Lone Pine-type order, under the circumstances presented in this case. We disagree. Section 802.08(4) provides in substance that if the party opposing a motion for summary judgment shows that the party cannot present facts. essential to justify the party's opposition, the court may refuse to grant the motion or may order a continuance to permit affidavits to be obtained or depositions taken or discovery to be had or make such other further order as is just. Thus, whether to refuse a motion for summary judgment in order to give an opposing party additional time to obtain essential facts to defeat summary judgment is a highly discretionary ruling. We have already concluded the trial court did not erroneously exercise its. discretion in declining to enter a Lone Pine order.
Finally, appellants assert that when it ordered dismissal of the cross claims with prejudice, the trial court unfairly precluded their bringing a future contribution claim against Seidl. Appellants treat the issue as one involving the exercise of discretion, but without briefing the appropriate scope of review.3 The parties cite *866no authority which prevents a trial court from dismissing a complaint with prejudice on summary judgment. We decline to review an issue inadequately briefed. State v. Pettit, 171 Wis. 2d 627, 647, 492 N.W.2d 633, 642 (Ct. App. 1992).
By the Court. — Judgment affirmed.
D. Alan Rudin, Strategies in Litigating Multiple Plaintiff Toxic Tort Suits, in ENVIRONMENTAL LITIGATION 122, 137-42 (Janet S. Kole et. al. eds. 1991). Rudin states that Lone Pine orders are useful to achieve efficiency and economy in toxic tort cases. Because numerous plaintiffs are usually involved, discovery is difficult to control, and a case management order (CMO) can regulate the process. A CMO can avoid duplication of effort by allowing common issues and claims to be identified and addressed en masse. Because of the unknown properties of certain chemicals, the individualized nature of each plaintiffs medical and social history, and the long latency period of certain ailments, establishing a causal relationship between an injury and chemical exposure is often difficult. A Lone Pine CMO forces plaintiffs to substantiate exposure, injury and causation. Rudin concludes that these are some of the reasons why CMOs play an increasing role in toxic tort litigation. Id. at 141-42. Appellants do not discuss the advantages of a Lone Pine CMO, except to argue that the trial court should have ordered one to benefit them.
As of the date of the hearing, Seidl had incurred investigation expenses amounting to $38,466.17 and legal expenses amounting to about $63,500.
Compare Potts v. Farmers Mut. Automobile Ins. Co., 233 Wis. 313, 318, 289 N.W. 606, 609 (1940) (trial court apparently *866erred as a matter of law when it granted summary judgment dismissing a complaint without prejudice), with Pattermann v. Whitewater, 32 Wis. 2d 350, 360-61, 145 N.W.2d 705, 710 (1966) (summary judgment dismissing complaint should have been without prejudice, to allow plaintiff to file claim against city under § 62.25, Stats., 1963, where document previously filed was only a notice of injury and not a claim).